A high-performance epitaxial wafer for photodetector chips

Abstract

The present invention discloses a high-performance optical detector chip epitaxial wafer, which includes an InP substrate layer and an epitaxial layer. The epitaxial layer is provided on the InP substrate layer, and the epitaxial layer includes a buffer layer, a first collection layer, a second collection layer, a lower waveguide layer, a cliff layer, a lower transition layer, an upper transition layer, a P-type multiple quantum well absorption layer, an upper waveguide layer, a P-type blocking layer, a P-type capping layer, and a P-type contact layer. Through the setting of corresponding mechanisms on the chip epitaxial wafer, the present invention is mainly aimed at the on-chip integrated application of waveguide-type detectors with high sensitivity, high speed, and high saturation power in the 1550 nm communication band. Utilizing the flexible energy band engineering of the III-V multi-component system, by designing the P-type majority carrier absorption layer, the carrier diffusion blocking layer, the transition layer, and the collection layer to adjust the electric field, strengthening the contribution of the electron flow to the photocurrent, and avoiding many adverse effects brought by the slow hole movement speed. By introducing the upper and lower waveguide layers, the confinement of photons in the waveguide is strengthened, and the detector responsivity is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor optoelectronic devices, and particularly relates to a high-performance photodetector chip epitaxial wafer. Background Art

[0002] Semiconductor photodetectors are the most ideal photodetectors due to their small size, high sensitivity, fast response speed, and easy integration. Typical ones include PIN photodiodes and avalanche diodes, which are widely used in fiber optic communication, sensing systems, high-energy physics, nuclear medicine, etc. A PIN photodiode is a detector with a lightly doped intrinsic region added between a pn diode. The internal electric field across both ends changes with the distance from the diode surface. The electric field in the intrinsic region of the PIN photodiode is very strong. When a photon is absorbed in this region, the photon energy is converted into new carriers (electron-hole pairs). These newly generated carriers drift in different directions under the action of the electric field according to their own polarities (electrons towards the n-region and holes towards the P-region). If an external circuit is connected, a photocurrent is generated at this time.

[0003] Single-carrier high-speed detectors are a new type of high-speed detector. In large-capacity fiber optic communication systems and ultra-high-speed test systems, photodiodes that can simultaneously meet the requirements of high response speed and high saturation output power are becoming the focus of attention. Because the optical receiver composed of such a photodiode and an optical amplifier has better performance than the optical receiver composed of an ordinary photodiode (pin-PD) and a post-stage electrical amplifier, the electrical amplifier can be omitted, expanding the bandwidth while simplifying the structure of the receiver. As a new type of photodetector, its unique working mode and characteristics such as high speed and high saturation output have attracted great attention from professionals in the technical research field and the industrial and industrial circles, and have a very broad market prospect. Currently, some research institutions represented by the NTT Photonics Laboratory in Japan have made quite great progress in the research and development and application of high saturation output and high-speed InGaAsPDs.

[0004] The traditional pin-PD light absorption layer is an intrinsic (unintentionally doped n-type) layer, which is completely depleted under the operating voltage. In the depletion layer, the photogenerated electrons and holes act as active carriers. Because the mobility of holes is lower than that of electrons, when high-power light is incident, a large number of holes still remaining in the depletion layer produce a space charge effect, thereby limiting the maximum output voltage value of the device. In order to overcome this problem, people have adopted a single-file carrier structure, the UTC-PD composed of a p-type neutral InGaAs light absorption layer and an n-type wide-bandgap InP assembly layer. The depletion assembly layer and the light absorption layer are completely separated in space. The photogenerated electron-hole pairs generated in the absorption layer diffuse to both ends of the absorption layer at the same time. The p-type diffusion blocking layer near the anode end prevents the electrons from diffusing to the anode, so that the electrons diffuse only in the direction of the assembly layer, that is, a single-file carrier is formed.

[0005] When the absorption layer diffuses electrons and injects them into the assembly layer, the electrons pass through the layer at high speed (4×107cm / s) due to the overshoot effect under the action of the internal electric field established by the conduction band barrier of the heterojunction interface. The photogenerated holes in the absorption layer are the majority carriers, and their dielectric relaxation time is very short, so the impact on the working speed of the photoelectrode tube can be ignored. The difference from the traditional pin-PD is that the bandwidth of UTC-PD depends on the diffusion time of electrons in the absorption layer and the drift time of the assembly layer. When the assembly layer is thin enough, the delay time of electrons in the assembly layer is about 0.2~0.4ps, which is negligible compared with the response time t of the absorption layer. The bandwidth of UTC-PD is mainly determined by the diffusion time of electrons in the absorption layer. Because the diffusion time of electrons is longer than the drift time of electrons, the speed performance of UTC-PD can be improved by utilizing a light absorption layer with a built-in field. The built-in field in the absorption layer causes a drift component in the electron transport, which is conducive to the faster movement of electrons to the assembly layer.

[0006] In order to achieve ultra-high-speed operation of UTC-PD, it is necessary to make full use of the characteristic of electron speed overshoot in the collection layer. The electron overshoot speed is about one order of magnitude higher than the saturation speed of holes, which effectively suppresses the space charge effect in the depletion layer. This makes UTC-PD still have a high output saturation current at high operating speeds compared to pin-PD. Even under low bias conditions, high-speed and high-saturation output performance can still be maintained, which is attributed to the depletion layer under relatively low electric fields.

[0007] The current UTC-PD structure does not have a waveguide confinement layer. This type of detector is mainly used for surface detectors and is not suitable for monolithic integration applications or waveguide detectors.

[0008] Therefore, in view of the above technical problems, it is necessary to provide a high-performance photodetector chip epitaxial wafer. Summary of the invention

[0009] The object of the present invention is to provide a high-performance epitaxial wafer for a photodetector chip to solve the above problems.

[0010] To achieve the above object, the technical solution provided by an embodiment of the present invention is as follows:

[0011] A high-performance epitaxial wafer for a photodetector chip, comprising: an InP substrate layer and an epitaxial layer;

[0012] An epitaxial layer is provided on the InP substrate layer, and the epitaxial layer includes a buffer layer, a first collection layer, a second collection layer, a lower waveguide layer, a cliff layer, a lower transition layer, an upper transition layer, a P-type multiple quantum well absorption layer, an upper waveguide layer, a P-type blocking layer, a P-type capping layer, and a P-type contact layer, and the buffer layer, the first collection layer, the second collection layer, the lower waveguide layer, the cliff layer, the lower transition layer, the upper transition layer, the P-type multiple quantum well absorption layer, the upper waveguide layer, the P-type blocking layer, the P-type capping layer, and the P-type contact layer are arranged in sequence.

[0013] Further, the InP substrate layer is semi-insulating or N-type, the semi-insulating is a doped iron substrate, and the N doping concentration is greater than 1x10 18 cm -3 , and the thickness is 100 - 400 microns.

[0014] Further, the doping concentration of the buffer layer is 1x10 18 cm -3 , the thickness is 0.2 - 0.5 microns, the first collection layer is an n-type highly doped InP material, the thickness is 50 - 100 nm, and the doping concentration is greater than 3x10 18 cm -3 .

[0015] Further, the second collection layer is an n-type low-doped InP material, the thickness is 200 - 300 nm, and the doping concentration is about 4x10 16 cm -3 .

[0016] Further, the lower waveguide layer is an n-type low-doped InGaAsP material, the thickness is 100 - 150 nm, and the doping concentration is about 2x10 16 cm -3 , the cliff layer is an n-type InP material, the thickness is 5 - 15 nm, and the doping concentration is about 1x10 18 cm -3 .

[0017] Further, the lower transition layer is an i-type InGaAsP material, the thickness is 10 - 20 nm, and the doping concentration is 1x10 15 cm -3On the left and right, the upper transition layer is made of type-I InGaAs material with a thickness of 5 - 15 nm and a doping concentration of 1x10 15 cm -3 or so.

[0018] Furthermore, the P-type multiple quantum well absorption layer is made of InGaAs / InGaAsP multiple quantum well material, and the doping concentration of the P-type doped multiple quantum well absorption layer is 1x10 18 cm -3 , and the total thickness is 50 - 100 nm.

[0019] Furthermore, the upper waveguide layer is made of p-type lightly doped InGaAsP material with a thickness of 100 - 150 nm and a doping concentration of 2x10 16 cm -3 or so, and the P-type blocking layer is made of P-type InGaAsP material with a doping concentration greater than 1x10 19 cm -3 , and the total thickness is 20 - 30 nm.

[0020] Furthermore, the P-type cap layer is made of P-type InP material with a doping concentration greater than 5x10 18 cm -3 , and the total thickness is 1 micron.

[0021] Furthermore, the P-type contact layer is made of P-type InGaAs material with a doping concentration greater than 2x10 19 cm -3 , and the total thickness is 100 - 200 nm.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] Through the setting of corresponding mechanisms on the chip epitaxial wafer, the present invention is mainly aimed at the on-chip integrated application of waveguide-type detectors with high sensitivity, high speed, and high saturation power in the 1550 nm communication band. By using the flexible energy band engineering of the III-V multi-component system, through the design of the P-type majority carrier absorption layer, the carrier diffusion blocking layer, the transition layer and the collection layer to adjust the electric field, strengthen the contribution of the electron flow to the photocurrent, and avoid many adverse effects brought by the slow hole movement speed. By introducing the upper and lower waveguide layers, the confinement of photons in the waveguide is strengthened, and the detector responsivity is improved. Description of the Drawings

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a schematic diagram of an epitaxial wafer of a high-performance photodetector chip in an embodiment of the present invention.

[0026] In the figure: 1. InP substrate layer, 2. epitaxial layer, 201. buffer layer, 202. first collection layer, 203. second collection layer, 204. lower waveguide layer, 205. cliff layer, 206. lower transition layer, 207. upper transition layer, 208. P-type multiple quantum well absorption layer, 209. upper waveguide layer, 210. P-type blocking layer, 211. P-type capping layer, 212. P-type contact layer. Specific embodiments

[0027] The present invention will be described in detail below in conjunction with the embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodical, or functional transformations made by those of ordinary skill in the art based on these embodiments are included within the protection scope of the present invention.

[0028] The present invention discloses an epitaxial wafer of a high-performance photodetector chip. Refer to Figure 1 as shown, it includes: an InP substrate layer 1 and an epitaxial layer 2.

[0029] Refer to Figure 1 as shown, an epitaxial layer 2 is provided on the InP substrate layer 1. The epitaxial layer 2 includes a buffer layer 201, a first collection layer 202, a second collection layer 203, a lower waveguide layer 204, a cliff layer 205, a lower transition layer 206, an upper transition layer 207, a P-type multiple quantum well absorption layer 208, an upper waveguide layer 209, a P-type blocking layer 210, a P-type capping layer 211, and a P-type contact layer 212. The buffer layer 201, the first collection layer 202, the second collection layer 203, the lower waveguide layer 204, the cliff layer 205, the lower transition layer 206, the upper transition layer 207, the P-type multiple quantum well absorption layer 208, the upper waveguide layer 209, the P-type blocking layer 210, the P-type capping layer 211, and the P-type contact layer 212 are arranged in sequence.

[0030] Refer to Figure 1 as shown, the InP substrate layer 1 is semi-insulating or N-type. The semi-insulating one is a doped iron substrate, and the N-doping concentration is greater than 1x10 18 cm -3 , and the thickness is 100 - 400 microns

[0031] Reference Figure 1 As shown, the doping concentration of the buffer layer 201 is 1x10 18 cm -3 , the thickness is 0.2 - 0.5 microns. The first collector layer 202 is an n-type highly doped InP material, the thickness is 50 - 100 nm, and the doping concentration is greater than 3x10 18 cm -3 .

[0032] Reference Figure 1 As shown, the second collector layer 203 is an n-type low-doped InP material, the thickness is 200 - 300 nm, and the doping concentration is 4x10 16 cm -3 or so.

[0033] Reference Figure 1 As shown, the lower waveguide layer 204 is an n-type low-doped InGaAsP material, the thickness is 100 - 150 nm, and the doping concentration is 2x10 16 cm -3 or so. The cliff layer 205 is an n-type InP material, the thickness is 5 - 15 nm, and the doping concentration is 1x10 18 cm -3 or so.

[0034] Reference Figure 1 As shown, the lower transition layer 206 is an i-type InGaAsP material, the thickness is 10 - 20 nm, and the doping concentration is 1x10 15 cm -3 or so. The upper transition layer 207 is an i-type InGaAs material, the thickness is 5 - 15 nm, and the doping concentration is 1x10 15 cm -3 or so.

[0035] Reference Figure 1 As shown, the P-type multi-quantum well absorption layer 208 is an InGaAs / InGaAsP multi-quantum well material. The doping concentration of the P-type doped multi-quantum well absorption layer is 1x10 18 cm -3 , and the total thickness is 50 - 100 nm.

[0036] Reference Figure 1 As shown, the upper waveguide layer 209 is a p-type low-doped InGaAsP material, the thickness is 100 - 150 nm, and the doping concentration is 2x10 16 cm -3 or so. The P-type blocking layer 210 is a P-type InGaAsP material, and the doping concentration is greater than 1x10 19 cm -3 , and the total thickness is 20 - 30 nm.

[0037] Reference Figure 1 As shown, the P-type cap layer 211 is made of P-type InP material with a doping concentration greater than 5x10 18 cm -3 , and the total thickness is 1 micron.

[0038] Reference Figure 1 As shown, the P-type contact layer 212 is made of P-type InGaAs material with a doping concentration greater than 2x10 19 cm -3 , and the total thickness is 100 - 200 nm.

[0039] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0040] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation manners understandable to those skilled in the art.

Claims

1. A high-performance optical detector chip epitaxial wafer, Characterized in that, Comprising: An InP substrate layer (1); An epitaxial layer (2) provided on the InP substrate layer (1), the epitaxial layer (2) includes a buffer layer (201), a first collection layer (202), a second collection layer (203), a lower waveguide layer (204), a cliff layer (205), a lower transition layer (206), an upper transition layer (207), a P-type multiple quantum well absorption layer (208), an upper waveguide layer (209), a P-type blocking layer (210), a P-type capping layer (211) and a P-type contact layer (212), the buffer layer (201), the first collection layer (202), the second collection layer (203), the lower waveguide layer (204), the cliff layer (205), the lower transition layer (206), the upper transition layer (207), the P-type multiple quantum well absorption layer (208), the upper waveguide layer (209), the P-type blocking layer (210), the P-type capping layer (211) and the P-type contact layer (212) are arranged in sequence, the InP substrate layer (1) is semi-insulating or N-type, the semi-insulating is a doped iron substrate, the N doping concentration is greater than 1x1018 cm-3, and the thickness is 100-400 microns, the doping concentration of the buffer layer (201) is 1x1018 cm-3, and the thickness is 0.2-0.5 microns, the first collection layer (202) is an n-type highly doped InP material, the thickness is 50-100 nm, and the doping concentration is greater than 3x1018 cm-3.

2. A high-performance optical detector chip epitaxial wafer according to claim 1, Characterized in that, The second collection layer (203) is an n-type low-doped InP material, the thickness is 200-300 nm, and the doping concentration is about 4x1016 cm-3.

3. A high-performance optical detector chip epitaxial wafer according to claim 1, Characterized in that, The lower waveguide layer (204) is an n-type low-doped InGaAsP material, the thickness is 100-150 nm, and the doping concentration is about 2x1016 cm-3, the cliff layer (205) is an n-type InP material, the thickness is 5-15 nm, and the doping concentration is about 1x1018 cm-3.

4. A high-performance optical detector chip epitaxial wafer according to claim 1, Characterized in that, The lower transition layer (206) is an i-type InGaAsP material, the thickness is 10-20 nm, and the doping concentration is about 1x1015 cm-3, the upper transition layer (207) is an i-type InGaAs material, the thickness is 5-15 nm, and the doping concentration is about 1x1015 cm-3.

5. A high-performance optical detector chip epitaxial wafer according to claim 1, Characterized in that, The P-type multiple quantum well absorption layer (208) is an InGaAs / InGaAsP multiple quantum well material, the P-type doped multiple quantum well absorption layer doping concentration is 1x1018 cm-3, and the total thickness is 50-100 nm.

6. A high-performance optical detector chip epitaxial wafer according to claim 1, Characterized in that, The upper waveguide layer (209) is made of p-type lightly doped InGaAsP material, with a thickness of 100 - 150 nm and a doping concentration of about 2x1016 cm-3. The P-type blocking layer (210) is made of P-type InGaAsP material, with a doping concentration greater than 1x1019 cm-3 and a total thickness of 20 - 30 nm.

7. A high-performance photodetector chip epitaxial wafer according to claim 1, characterized in that the P-type capping layer (211) is made of P-type InP material, with a doping concentration greater than 5x1018 cm-3 and a total thickness of 1 micron.

8. A high-performance photodetector chip epitaxial wafer according to claim 1, characterized in that the P-type contact layer (212) is made of P-type InGaAs material, with a doping concentration greater than 2x1019 cm-3 and a total thickness of 100 - 200 nm.

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