Semiconductor optical position detector and semiconductor optical position detector array

Abstract

To provide a semiconductor optical position detector capable of inhibiting increase of noise regardless of the material, and to provide a semiconductor optical position detector array.SOLUTION: A semiconductor optical position detector 1 includes a first semiconductor layer 10, a second semiconductor layer 20 laminated on the first semiconductor layer 10, and a plurality of semiconductor regions 30 extending from the second semiconductor layer 20 to the first semiconductor layer 10. The semiconductor regions 30 have: a first contact region 31 in contact with a first metal electrode 41; a second contact region 32 in contact with a second metal electrode 42; and a plurality of island regions 33. Each of the island regions 33 is enclosed by an enclosure region 50 and does not contact with electrodes.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to semiconductor optical position detectors and semiconductor optical position detector arrays. [Background technology]

[0002] Patent Document 1 describes a one-dimensional position detector. In this position detector, an InGaAs layer (i-layer) and a p-type InP layer are formed on an n-type InP substrate. A cathode electrode is formed on the back surface of the n-type InP substrate, and a pair of electrodes are formed on both ends of the front surface of the p-type InP layer. In this position detector, a photocurrent generated in response to incident light is divided in inverse proportion to the resistance value to the pair of electrodes and detected at each of the pair of electrodes. Then, the incident position is obtained based on the ratio of the currents at each of the pair of electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-033507 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above technical field, there is a demand for making a position detector using a compound semiconductor material. However, it is difficult to make an element with a low carrier concentration in a compound semiconductor, so the resistance between the electrodes tends to be low. In that case, a current flows between the electrodes in response to a small potential difference, which may increase noise.

[0005] An object of the present disclosure is to provide a semiconductor optical position detector and a semiconductor optical position detector array that are capable of suppressing an increase in noise without relying on materials. [Means for solving the problem]

[0006] The semiconductor optical position detector according to the present disclosure includes: [1] "a first semiconductor layer made of a first compound semiconductor and having a first conductivity type; a second semiconductor layer stacked on the first semiconductor layer and having a band gap energy larger than that of the first compound semiconductor; a plurality of semiconductor regions having a second conductivity type different from the first conductivity type formed in the second semiconductor layer so as to extend from a surface of the second semiconductor layer opposite to the first semiconductor layer toward the first semiconductor layer; an enclosing region formed in the second semiconductor layer and surrounding at least a portion of the plurality of semiconductor regions; and first metasemiconductors provided on the second semiconductor layer and arranged to be spaced apart from each other along a second direction intersecting a first direction which is a stacking direction of the first semiconductor layer and the second semiconductor layer. a first contact region in contact with the first metal electrode, a second contact region in contact with the second metal electrode and arranged along the second direction while being spaced apart from the first contact region, and a plurality of island regions arranged along the second direction between the first contact region and the second contact region as viewed from the first direction, wherein a carrier concentration of the second conductivity type in the surrounding region is lower than a peak of a carrier concentration of the second conductivity type in the island region, and each of the plurality of island regions is surrounded by the surrounding region as viewed from the first direction and is not in contact with an electrode.

[0007] In this detector, a plurality of semiconductor regions of a second conductivity type extending from the second semiconductor layer toward the first semiconductor layer are formed in a second semiconductor layer in which a first metal electrode and a second metal electrode spaced apart from each other are formed. The plurality of semiconductor regions include a plurality of island regions arranged in the arrangement direction (second direction) of the first metal electrode and the second metal electrode between a first contact region and a second contact region in contact with the first metal electrode and the second metal electrode, respectively. Each of the plurality of island regions is surrounded by a surrounding region in which the carrier concentration of the second conductivity type is lower than the peak of the carrier concentration of the second conductivity type in the island region, and is not in contact with the electrode. By forming the island region as described above between the first metal electrode (first contact region) and the second metal electrode (second contact region), an energy barrier is formed between the island regions, and the resistance between the first metal electrode and the second metal electrode can be increased. Therefore, according to this detector, it is possible to suppress an increase in noise caused by the structure of the island region, regardless of the material. The second conductivity type carrier concentration in the surrounding region being lower than the peak of the second conductivity type carrier concentration in the island region includes cases where the surrounding region is of the second conductivity type but the second conductivity type carrier concentration is lower than the peak, and cases where the surrounding region is not of the second conductivity type (for example, the first conductivity type is dominant) and therefore the second conductivity type carrier concentration is lower than the peak. Therefore, the conductivity type of the surrounding region is not limited.

[0008] The semiconductor optical position detector according to the present disclosure may be [2] "the semiconductor optical position detector according to the above [1], in which the plurality of semiconductor regions are formed from the second semiconductor layer to the inside of the first semiconductor layer." In this way, by forming the second conductivity type semiconductor region inside the first semiconductor layer, sensitivity can be obtained without applying a voltage. This eliminates the need to prepare a voltage source and enables measurement with a low dark current.

[0009] The semiconductor optical position detector according to the present disclosure may be [3] "the semiconductor optical position detector according to the above [1] or [2], comprising a third metal electrode and a fourth metal electrode provided on the second semiconductor layer and arranged to be spaced apart from each other along a third direction intersecting the first direction and the second direction, the plurality of semiconductor regions having a third contact region in contact with the third metal electrode and a fourth contact region in contact with the fourth metal electrode and arranged to be spaced apart from the third contact region along the third direction, and the plurality of island regions are arranged along the third direction between the third contact region and the fourth contact region." In this case, it is possible to obtain two-dimensional position information including the second direction and the third direction based on the output currents from each of the first metal electrode to the fourth metal electrode.

[0010] The semiconductor optical position detector according to the present disclosure may be the semiconductor optical position detector according to any one of the above items [1] to [3], wherein [4] "the surrounding region has the second conductivity type, and the lowest carrier concentration of the second conductivity type in the surrounding region is 3 / 4 or less of the peak carrier concentration of the second conductivity type in the island region. In this case, by lowering the carrier concentration, the energy barrier can be made higher, and the resistance between the first metal electrode and the second metal electrode can be made higher."

[0011] The semiconductor optical position detector according to the present disclosure is, [5] "the second semiconductor layer has the first conductivity type, and the carrier concentration of the first conductivity type of the second semiconductor layer is 1×10 16 The semiconductor optical position detector according to any one of the above [1] to [4] may be configured as follows. In this case, it is possible to suppress an unnecessary increase in resistance between the first metal electrode and the second metal electrode, and to suppress deterioration of linearity.

[0012] The semiconductor optical position detector according to the present disclosure may be [6] "the semiconductor optical position detector according to any one of the above [1] to [5], including a resistance adjustment region formed between the adjacent island regions." In this case, it is possible to prevent the resistance from increasing too much, and to detect even high-intensity light with good linearity. Note that the resistance adjustment region is, for example, a region outside the island region where the carrier concentration is relatively high due to overlapping of regions where the carrier concentration decreases with distance from the island region.

[0013] The semiconductor optical position detector according to the present disclosure may be [7] "the semiconductor optical position detector according to any one of the above [1] to [6], wherein each of the plurality of island regions is circular when viewed from the first direction." For example, if the island regions are polygonal, there is a risk of electric field concentration at the corners. In contrast, by making the island regions circular in this way, electric field concentration in a portion can be avoided, and it is possible to apply the electric field uniformly. In addition, by minimizing the side closest to the circles, it is possible to prevent an unnecessary decrease in resistance.

[0014] The semiconductor optical position detector according to the present disclosure is, [8] "The carrier concentration of the second conductivity type in the semiconductor region is 1×10 17 cm -3 The semiconductor optical position detector according to any one of the above items [1] to [7] may be provided. In this case, by increasing the carrier concentration, the barrier at the time of the PN junction can be increased, and the dark current can be reduced.

[0015] The semiconductor optical position detector according to the present disclosure may be [9] "the semiconductor optical position detector according to any one of the above [1] to [8], wherein the first semiconductor layer is made of any one of InGaAs, InAs, InAsSb, GaAs, GaN, and InGaN, or a mixed crystal thereof, and the second semiconductor layer is made of any one of InP, InAsP, AlInP, AlInAsP, and GaN, or a mixed crystal thereof." In this way, it is possible to fabricate an optical position detector even from a compound semiconductor, which is difficult to fabricate an optical position detector from, and it is possible to fabricate an optical position detector with a high S / N ratio that is tailored to the wavelength according to each material.

[0016] The semiconductor optical position detector array according to the present disclosure is

[10] "a semiconductor optical position detector array including a plurality of the semiconductor optical position detectors according to any one of the above [1)] to [9], the plurality of the semiconductor optical position detectors being arranged along a direction intersecting the first direction and the second direction." In this case, even when a plurality of light beams are incident, it is possible to easily separate and detect signals corresponding to the respective light beams. Effect of the Invention

[0017] According to the present disclosure, it is possible to provide a semiconductor optical position detector and a semiconductor optical position detector array that are capable of suppressing an increase in noise without relying on materials. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing a semiconductor optical position detector according to the present embodiment. [Diagram 2] FIG. 2 is a schematic plan view showing an enlarged view of the islanded region and the surrounded region shown in FIG. [Diagram 3] FIG. 3 is a graph showing carrier concentrations in the semiconductor region shown in FIG. [Figure 4] FIG. 4 is a schematic plan view showing a semiconductor optical position detector according to a modified example. [Diagram 5] FIG. 5 is a schematic plan view showing a semiconductor optical position detector according to a modified example. [Figure 6] FIG. 6 is a schematic plan view showing another modified example. [Figure 7] FIG. 7 is a schematic cross-sectional view showing still another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, a semiconductor optical position detector and a semiconductor optical position detector array according to an embodiment will be described with reference to the drawings. In the description of each drawing, the same or corresponding elements are given the same reference numerals, and duplicated descriptions may be omitted. In addition, each drawing may illustrate an orthogonal coordinate system defined by an X-axis, a Y-axis, and a Z-axis.

[0020] FIG. 1 is a schematic diagram showing a semiconductor optical position detector according to this embodiment. FIG. 1(a) is a plan view, and FIG. 1(b) is a cross-sectional view taken along line Ib-Ib in FIG. 1. As shown in FIG. 1, the semiconductor optical position detector 1 includes a first semiconductor layer 10, a second semiconductor layer 20, a first metal electrode 41 and a second metal electrode 42, a common electrode 45, a plurality of semiconductor regions 30, and a protective film F. The semiconductor optical position detector 1 has a front surface 1a and a back surface 1b opposite to the front surface 1a. In the semiconductor optical position detector 1, for example, the front surface 1a is set as a light incident surface.

[0021] The semiconductor optical position detector 1 is, for example, a (one-dimensional) PSD (Position Sensitive Detector) that detects the incident position of light. In this case, when spot light is incident on the semiconductor optical position detector 1 from the front surface 1a side, an electric charge proportional to the amount of light is generated at the incident position. This electric charge reaches the second semiconductor layer 20 as a photocurrent, is divided inversely proportional to the distance to the first metal electrode 41 and the second metal electrode 42, and is extracted from the first metal electrode 41 and the second metal electrode 42. Then, the incident position of the spot light is obtained based on the value of the output current from the first metal electrode 41 and the second metal electrode 42, the distance from the incident position to the first metal electrode 41 and the second metal electrode 42, and the like, regardless of the amount of incident light, etc.

[0022] The first semiconductor layer 10 is made of a first compound semiconductor and has a first conductivity type (e.g., n-type). The first compound semiconductor is, for example, any one of InGaAs, InAs, InAsSb, GaAs, GaN, and InGaN, or a mixed crystal thereof. The first semiconductor layer 10 includes a back surface 1b. The first semiconductor layer 10 includes a plurality of semiconductor layers stacked along a first direction (here, the Z-axis direction) intersecting with the front surface 1a. The plurality of semiconductor layers include, for example, a substrate (not shown), a buffer layer (not shown), and a light absorption layer (not shown) stacked in this order from the back surface 1b side.

[0023] The substrate and the buffer layer are made of InP, for example. The buffer layer has a thickness of, for example, about 0.5 μm to 2.0 μm in the first direction. The light absorption layer includes (is made of) InGaAs, for example. For example, the light absorption layer has a thickness of, for example, about 1.0 μm to 5 μm in the first direction.

[0024] The second semiconductor layer 20 is laminated on the first semiconductor layer 10. The second semiconductor layer 20 has a band gap energy larger than the band gap energy of the first compound semiconductor. The second semiconductor layer 20 has a first conductivity type (e.g., n-type). The carrier concentration of the first conductivity type of the second semiconductor layer 20 is, for example, 1×10 16 cm -3 The second compound semiconductor is, for example, any one of InP, InAsP, AlInP, AlInAsP, and GaN, or a mixed crystal of these.

[0025] The second semiconductor layer 20 includes a front surface 1a. A first direction (here, the Z-axis direction) is a direction intersecting the front surface 1a and the back surface 1b, and is also a stacking direction of the first semiconductor layer 10 and the second semiconductor layer 20. The second semiconductor layer 20 includes at least one cap layer (not shown). The cap layer is stacked on the light absorbing layer on the front surface 1a side of the light absorbing layer, and has an interface with the light absorbing layer.

[0026] Here, a recess 60 is formed on the surface 1a. As an example, the surface 1a has a rectangular shape when viewed from a first direction, and the recess 60 has a rectangular shape similar to that of the surface 1a when viewed from the first direction. The recess 60 includes a bottom surface 60i and a side surface 60s connecting the bottom surface 60i and the surface 1a. The second semiconductor layer 20 (e.g., a cap layer) is exposed on the bottom surface 60i of the recess 60.

[0027] The first semiconductor layer 10 and the second semiconductor layer 20 include a first region A overlapping with the bottom surface 60i of the recess 60 when viewed from the first direction, and a second region B outside the first region A. In the semiconductor optical position detector 1, the first region A overlapping with the bottom surface 60i of the recess 60 when viewed from the first direction is configured to be thinner than the second region B outside the bottom surface 60i, and serves as a light receiving section that generates electric charges upon receiving incident light.

[0028] The protective film F is provided so as to cover the front surface 1a, the side surface 60s of the recess 60, and the bottom surface 60i of the recess 60. The protective film F may have a function as an anti-reflection film. A through hole Fh is formed in the protective film F on the second region B, and the second semiconductor layer 20 (a first contact region 31 and a second contact region 32 described later) is exposed from the through hole Fh. The first metal electrode 41 and the second metal electrode 42 are arranged so as to be spaced apart from each other along a second direction (here, the X-axis direction) intersecting the first direction, and are formed on the second semiconductor layer 20 via the protective film F. The first metal electrode 41 and the second metal electrode 42 are in contact with the second semiconductor layer 20 via the through hole Fh. The common electrode 45 is formed on the back surface 1b and in contact with the first semiconductor layer 10 (for example, a substrate).

[0029] The semiconductor region 30 is formed in the second semiconductor layer 20 so as to extend from the surface (surface 1a) of the second semiconductor layer 20 opposite to the first semiconductor layer 10 toward the first semiconductor layer 10. In this embodiment, the semiconductor region 30 is formed from the second semiconductor layer 20 to the inside of the first semiconductor layer 10 (reaching the inside of the first semiconductor layer 10). The semiconductor region 30 has a second conductivity type (e.g., p-type) different from the first conductivity type. Note that the semiconductor region 30 does not have to reach the inside of the first semiconductor layer 10.

[0030] The semiconductor region 30 is made into a region of the second conductivity type by doping the second semiconductor layer 20 and the first semiconductor layer 10 with impurities (e.g., Zn). The semiconductor region 30 may be, for example, a diffusion region formed by doping the impurity from the front surface 1a side by thermal diffusion. Alternatively, the semiconductor region 30 may be formed by doping the impurity by ion implantation. The carrier concentration of the second conductivity type in the semiconductor region 30 is, for example, 1×10 17 cm -3 That's all.

[0031] The multiple semiconductor regions 30 include a first contact region 31, a second contact region 32, and multiple island regions 33. The first contact region 31 is in contact with a first metal electrode 41 via a through hole Fh in the protective film F. The second contact region 32 is in contact with a second metal electrode 42 via a through hole Fh in the protective film F. The second contact region 32 is arranged in the second direction while being spaced apart from the first contact region 31.

[0032] The island regions 33 are arranged along the second direction between the first contact region 31 and the second contact region 32. In this embodiment, the island regions 33 are arranged uniformly in a plane including the second direction and a third direction (here, the Y-axis direction) intersecting the first and second directions. The island regions 33 are circular when viewed from the first direction. The island regions 33 are spaced apart from each other. In this embodiment, the contact portion between the first metal electrode 41 and the first contact region 31 and the contact portion between the second metal electrode 42 and the second contact region 32 extend linearly over the entire range in which the island regions 33 are distributed in the third direction (over the entire first metal electrode 41 and the second metal electrode 42).

[0033] 1 and 2, the semiconductor optical position detector 1 includes a surrounding region 50 formed in the second semiconductor layer 20 and surrounding at least a portion of the semiconductor regions 30 when viewed from the first direction. The surrounding region 50 surrounds at least the island region 33 when viewed from the first direction.

[0034] The surrounding region 50 is formed in an annular shape (here, in a circular shape) around the island region 33. A non-diffusion region 51 is formed outside the surrounding region 50. In this embodiment, the surrounding region 50 is a region where impurity diffusion has spread when the island region 33 is formed. Therefore, as shown in FIG. 3, the surrounding region 50 is of the second conductivity type and has a carrier concentration lower than the carrier concentration of the second conductivity type of the island region 33. More specifically, the carrier concentration of the surrounding region 50 decreases with increasing radial distance from the center of the island region 33.

[0035] However, adjacent surrounding regions 50 have overlapping regions 52 at their outer edges, and the carrier concentrations in these overlapping regions 52 are high due to the sum of the carrier concentrations. Therefore, the overlapping regions 52 between the island regions 33 prevent the electrical resistance from becoming too high. In other words, the overlapping regions 52 are resistance adjusting regions. In yet other words, the semiconductor optical position detector 1 includes a resistance adjusting region formed between adjacent island regions 33. However, the resistance adjusting region is not essential and may not be provided.

[0036] The lowest second conductivity type carrier concentration Cβ in the surrounding region 50 is 3 / 4 or less of the peak value Cα of the second conductivity type carrier concentration in the island region 33. Alternatively, the carrier concentration Cβ is preferably 2 / 3 or less of the peak value Cα, and more preferably 1 / 2 or less. In this embodiment, the distance D2 between the closest island regions 33 is, for example, about 3 μm, which is smaller than the diameter D1 (for example, about 10 μm) of the island region 33. The non-diffusion region 51 may be of the first conductivity type.

[0037] As described above, each of the multiple island regions 33 is surrounded by the surrounding region 50 when viewed from the first direction, and is not in contact with an electrode. The island region 33 not in contact with an electrode means that in addition to not being in direct contact with the first metal electrode 41, the second metal electrode 42, etc., the island region 33 is not in contact with any member or layer having a lower resistance than the second semiconductor layer 20, such as wiring electrically connected to the first metal electrode 41 or the second metal electrode 42 or other electrodes.

[0038] As described above, in the semiconductor optical position detector 1, a plurality of semiconductor regions 30 of a second conductivity type extending from the second semiconductor layer 20 toward the first semiconductor layer 10 are formed in the second semiconductor layer 20 in which the first metal electrode 41 and the second metal electrode 42 spaced apart from each other are formed. The plurality of semiconductor regions 30 include a plurality of island regions 33 arranged in the second direction between the first contact region 31 and the second contact region 32 in contact with the first metal electrode 41 and the second metal electrode 42, respectively.

[0039] Each of the island regions 33 is surrounded by a surrounding region 50 having a second conductivity type carrier concentration lower than the peak of the second conductivity type carrier concentration in the island region 33, and is not in contact with an electrode. By forming the island regions 33 as described above between the first metal electrode 41 (first contact region 31) and the second metal electrode 42 (second contact region 32), an energy barrier is formed between the island regions 33, and the electrical resistance between the first metal electrode 41 and the second metal electrode 42 can be increased. Therefore, according to the semiconductor optical position detector 1, it is possible to suppress an increase in noise caused by the structure of the island regions 33, regardless of the material.

[0040] Moreover, in the semiconductor optical position detector 1, the multiple semiconductor regions 30 are formed from the second semiconductor layer 20 to the inside of the first semiconductor layer 10. In this way, by forming the second conductivity type semiconductor region 30 throughout the inside of the first semiconductor layer 10, sensitivity can be obtained without applying a voltage. This eliminates the need to prepare a voltage source and enables measurement with a low dark current.

[0041] Furthermore, in the semiconductor optical position detector 1, the surrounding region 50 has the second conductivity type, and the lowest second conductivity type carrier concentration Cβ in the surrounding region 50 is equal to or less than 3 / 4 of the peak value Cα of the second conductivity type carrier concentration in the island region 33. For this reason, by lowering the carrier concentration, the energy barrier can be made higher, and the resistance between the first metal electrode 41 and the second metal electrode 42 can be made higher.

[0042] In addition, in the semiconductor optical position detector 1, the second semiconductor layer 20 has a first conductivity type, and the carrier concentration of the first conductivity type of the second semiconductor layer 20 is 1×10 16 As a result, it is possible to prevent the resistance between first metal electrode 41 and second metal electrode 42 from increasing more than necessary, and to prevent deterioration of linearity.

[0043] The semiconductor optical position detector 1 also includes a resistance adjustment region (overlap region 52) formed between adjacent island regions 33. This prevents the resistance from increasing too much, and enables detection with good linearity even with high-intensity light. Note that the resistance adjustment region is, for example, a region outside the island region (surrounding region 50) where the carrier concentration is relatively high due to overlapping of regions (surrounding regions 50) where the carrier concentration decreases with increasing distance from the island region.

[0044] In the semiconductor optical position detector 1, each of the island regions 33 is circular when viewed from the first direction. By making the island regions 33 circular in this way, it is possible to prevent the electric field from concentrating at the corners when the island regions 33 are polygonal, and it is possible to apply the electric field uniformly. In addition, by making the closest side between the circles minimal, it is possible to prevent an unnecessary decrease in resistance.

[0045] In addition, in the semiconductor optical position detector 1, the second conductivity type carrier concentration of the semiconductor region 30 is 1×10 17 / cm 3That is all. For this reason, by increasing the carrier concentration, the barrier at the PN junction can be increased and the dark current can be reduced.

[0046] Furthermore, in the semiconductor optical position detector 1, the first semiconductor layer 10 is made of any one of InGaAs, InAs, InAsSb, GaAs, GaN, and InGaN, or a mixed crystal thereof, and the second semiconductor layer 20 is made of any one of InP, InAsP, AlInP, AlInAsP, and GaN, or a mixed crystal thereof. In this way, it is possible to fabricate an optical position detector even from compound semiconductors, which are difficult to fabricate an optical position detector from, and it is possible to fabricate an optical position detector with a high S / N ratio that is tailored to the wavelength according to each material.

[0047] The above embodiment has been described as one aspect of the semiconductor optical position detector according to the present invention. Therefore, the present invention is not limited to the semiconductor optical position detector 1 according to the above embodiment, and may be modified as desired. Next, modified examples will be described.

[0048] FIG. 4 is a schematic plan view showing a semiconductor optical position detector according to a modified example. In the above embodiment, the island regions 33 each having a circular shape as viewed from the first direction are arranged two-dimensionally. However, as shown in FIG. 4(a), the island regions 33 may be formed in a long rectangular shape as viewed from the first direction. In the example of FIG. 4(a), a plurality of island regions 33 extending over the entire area sandwiched between the first metal electrode 41 and the second metal electrode 42 in the third direction are arranged one-dimensionally along the second direction while being spaced apart from each other. In this case, the shape of the surrounding region 50 surrounding the island region 33 may be a long rectangular ring shape that follows the outer shape of the island region 33.

[0049] 4B, the island region 33 may be formed in a square shape when viewed from the first direction. In the example of FIG. 4B, a plurality of island regions 33 each having a square shape when viewed from the first direction are uniformly arranged two-dimensionally along the second and third directions while being spaced apart from each other. In this case, the shape of the surrounding region 50 surrounding the island region 33 may be a square ring shape that follows the outer shape of the island region 33.

[0050] Furthermore, as shown in Fig. 5, the island region 33 may be formed in a hexagonal shape when viewed from the first direction. In the example of Fig. 5, a plurality of island regions 33 each having a hexagonal shape when viewed from the first direction are uniformly arranged two-dimensionally along the second and third directions while being spaced apart from each other. In this case, the shape of the surrounding region 50 surrounding the island region 33 may be a hexagonal ring shape that follows the outer shape of the island region 33. As described above, the island region 33 is not limited to a circular shape, and may be any polygonal shape. Furthermore, the island region 33 is not limited to a circular or polygonal shape, and may be any shape (for example, an elliptical shape).

[0051] Fig. 6 is a schematic plan view showing another modified example. As shown in Fig. 6(a), the semiconductor optical position detector 1 may further include a third metal electrode 43 and a fourth metal electrode 44. In the example of Fig. 6(a), the third metal electrode 43 and the fourth metal electrode 44 are arranged so as to be spaced apart from each other along the third direction. The semiconductor region 30 further includes a third contact region 35 in contact with the third metal electrode 43, and a fourth contact region 36 in contact with the fourth metal electrode 44 and arranged so as to be spaced apart from the third contact region 35 along the third direction.

[0052] The island regions 33 are arranged along the third direction between the third contact region 35 and the fourth contact region 36. Here, when viewed from the first direction, a plurality of circular island regions 33 are arranged two-dimensionally over the entire rectangular region surrounded by the first metal electrode 41 (first contact region 31), the second metal electrode 42 (second contact region 32), the third metal electrode 43 (third contact region 35), and the fourth metal electrode 44 (fourth contact region 36).

[0053] 6(a), the contact portion between the first metal electrode 41 and the first contact region 31 and the contact portion between the second metal electrode 42 and the second contact region 32 extend linearly over the entire range in which the island region 33 is distributed in the third direction (over the entire first metal electrode 41 and the second metal electrode 42). Also, the contact portion between the third metal electrode 43 and the third contact region 35 and the contact portion between the fourth metal electrode 44 and the fourth contact region 36 extend linearly over the entire range in which the island region 33 is distributed in the second direction (over the entire third metal electrode 43 and the fourth metal electrode 44).

[0054] According to the modified example of (a) in Figure 6 described above, it is possible to obtain two-dimensional position information including the second direction and the third direction based on the output currents from each of the first metal electrode 41, the second metal electrode 42, the third metal electrode 43, and the fourth metal electrode 44.

[0055] In the example of FIG. 6B, the first metal electrode 41, the second metal electrode 42, the third metal electrode 43, and the fourth metal electrode 44 are each formed in an L-shape by a portion extending along the second direction and a portion extending along the third direction. The first metal electrode 41, the second metal electrode 42, the third metal electrode 43, and the fourth metal electrode 44 are arranged such that a corner 41p of the first metal electrode 41, a corner 42p of the second metal electrode 42, a corner 43p of the third metal electrode 43, and a corner 44p of the fourth metal electrode 44 form the four corners of a rectangle. The first metal electrode 41 and the second metal electrode 42 are arranged to face each other along one diagonal line L12, and the third metal electrode 43 and the fourth metal electrode 44 are arranged to face each other along another diagonal line L34.

[0056] The first metal electrode 41 and the first contact region 31 are in contact only at the corner 41p, the second metal electrode 42 and the second contact region 32 are in contact only at the corner 42p, the third metal electrode 43 and the third contact region 35 are in contact only at the corner 43p, and the fourth metal electrode 44 and the fourth contact region 36 are in contact only at the corner 44p. Therefore, in the example of (b) in FIG. 6, the position detection directions are the direction along the diagonal line L12 and the direction along the diagonal line L34.

[0057] 6(b), by interpreting the direction along the diagonal line L12 as a new second direction and the direction along the diagonal line L34 as a new third direction, the first metal electrode 41 and the second metal electrode 42 are arranged at a distance from each other along the second direction, and the third metal electrode 43 and the fourth metal electrode 44 are arranged at a distance from each other along the third direction. Also, the island region 33 is arranged along the second direction and the third direction.

[0058] In addition, portions of the first metal electrode 41, the second metal electrode 42, the third metal electrode 43, and the fourth metal electrode 44 other than corners 41p, 42p, 43p, and 44p (portions not in contact with the semiconductor region 30) are provided for light shielding purposes to limit the light receiving area.

[0059] With the modified example of Figure 6 (b) described above, it is also possible to obtain two-dimensional position information including the second direction and the third direction based on the output currents from each of the first metal electrode 41, the second metal electrode 42, the third metal electrode 43, and the fourth metal electrode 44.

[0060] Furthermore, although not shown in the drawings, the semiconductor optical position detector 1 may be configured as a double-sided split PSD. In this case, a first metal electrode 41 and a second metal electrode 42 are formed on the front surface 1a, and a third metal electrode 43 and a fourth metal electrode 44 are formed on the back surface 1b.

[0061] FIG. 7 is a schematic cross-sectional view showing yet another modified example. The semiconductor optical position detector 1A shown in FIG. 7 is different from the semiconductor optical position detector 1 according to the embodiment in that it includes a first semiconductor layer 10A instead of the first semiconductor layer 10 and a second semiconductor layer 20A instead of the second semiconductor layer 20. The first semiconductor layer 10A includes a first layer 11 having a first conductivity type (e.g., n-type) and a second layer 12 having the first conductivity type and laminated on a part of the first layer 11. The first layer 11 is made of, for example, N-InP, and the second layer 12 is made of, for example, N-InGaAs. The second semiconductor layer 20A has a second conductivity type (e.g., p-type) and is laminated on the second layer 12 of the first semiconductor layer 10A. The second semiconductor layer 20A is made of, for example, P-InP.

[0062] The second semiconductor layer 20A includes a surface 1a. The semiconductor region 30 is formed in the second semiconductor layer 20A so as to extend from the surface (surface 1a) of the second semiconductor layer 20A opposite to the first semiconductor layer 10A toward the first semiconductor layer 10A. Here, the semiconductor region 30 is formed from the second semiconductor layer 20A to the inside of the first semiconductor layer 10A. In this manner, the semiconductor region 30 having the second conductivity type may be formed in the second semiconductor layer 20A having the second conductivity type. At this time, the carrier concentration of the second conductivity type in the second semiconductor layer 20A is, for example, 1×10 14 cm -3 ~1×10 16cm -3 It can be about that.

[0063] The above describes the semiconductor optical position detector 1, 1A, but a semiconductor optical position detector array may be formed by providing a plurality of the above semiconductor optical position detectors 1, 1A and arranging the plurality of semiconductor optical position detectors 1, 1A along a direction intersecting the first direction and the second direction. [Explanation of symbols]

[0064] 1,1A...semiconductor optical position detector, 10,10A...first semiconductor layer, 20,20A...second semiconductor layer, 30...semiconductor region, 31...first contact region, 32...second contact region, 33...island region, 35...third contact region, 36...fourth contact region, 41...first metal electrode, 42...second metal electrode, 43...third metal electrode, 44...fourth metal electrode, 50...surrounding region, 52...overlap region (resistance adjustment region).

Claims

1. a first semiconductor layer made of a first compound semiconductor and having a first conductivity type; a second semiconductor layer laminated on the first semiconductor layer and having a band gap energy larger than that of the first compound semiconductor; a plurality of semiconductor regions formed in the second semiconductor layer so as to extend from a surface of the second semiconductor layer opposite to the first semiconductor layer toward the first semiconductor layer, the semiconductor regions having a second conductivity type different from the first conductivity type; a surrounding region formed in the second semiconductor layer and surrounding at least a portion of the semiconductor regions; a first metal electrode and a second metal electrode provided on the second semiconductor layer and arranged to be spaced apart from each other along a second direction intersecting a first direction which is a stacking direction of the first semiconductor layer and the second semiconductor layer; Equipped with The plurality of semiconductor regions include a first contact region in contact with the first metal electrode; a second contact region in contact with the second metal electrode and arranged in the second direction while being spaced apart from the first contact region; a plurality of island regions arranged along the second direction between the first contact region and the second contact region when viewed from the first direction; having a peak concentration of the second conductive type carriers in the surrounding region is lower than a peak concentration of the second conductive type carriers in the island region; Each of the plurality of island regions is surrounded by the surrounding region when viewed from the first direction and is not in contact with an electrode. Semiconductor optical position detector.

2. The plurality of semiconductor regions are formed from the second semiconductor layer to the inside of the first semiconductor layer.

2. The semiconductor optical position detector according to claim 1.

3. a third metal electrode and a fourth metal electrode provided on the second semiconductor layer and arranged to be spaced apart from each other along a third direction intersecting the first direction and the second direction; The plurality of semiconductor regions include a third contact region in contact with the third metal electrode; a fourth contact region in contact with the fourth metal electrode and arranged along the third direction while being spaced apart from the third contact region; having The island regions are arranged along the third direction between the third contact region and the fourth contact region.

2. The semiconductor optical position detector according to claim 1.

4. the surrounding region has the second conductivity type; the lowest concentration of the second conductive type carriers in the surrounding region is 3 / 4 or less of the peak concentration of the second conductive type carriers in the island region; 2. The semiconductor optical position detector according to claim 1.

5. the second semiconductor layer has the first conductivity type; The second semiconductor layer has a carrier concentration of the first conductivity type of 1×10 １６ cm －３ Below is the 2. The semiconductor optical position detector according to claim 1.

6. a resistance adjusting region formed between adjacent island regions; 2. The semiconductor optical position detector according to claim 1.

7. Each of the plurality of island regions is circular when viewed from the first direction.

2. The semiconductor optical position detector according to claim 1.

8. The carrier concentration of the second conductivity type in the semiconductor region is 1×10 １７ cm －３ That's all.

2. The semiconductor optical position detector according to claim 1.

9. The first semiconductor layer is made of any one of InGaAs, InAs, InAsSb, GaAs, GaN, and InGaN, or a mixed crystal thereof, The second semiconductor layer is made of any one of InP, InAsP, AlInP, AlInAsP, and GaN, or a mixed crystal thereof.

2. The semiconductor optical position detector according to claim 1.

10. A plurality of the semiconductor optical position detectors according to any one of claims 1 to 9 are provided, The semiconductor optical position detectors are arranged along a direction intersecting the first direction and the second direction. Semiconductor optical position sensitive detector array.

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