Luminous element and manufacturing method thereof

[0031] figure 1 The first embodiment of the light-emitting epitaxial structure of the light-emitting element according to the present invention is disclosed. The light-emitting epitaxial structure 1 includes a growth substrate 10, a contact layer 20 formed on the growth substrate 10, a process conversion layer 31 formed on the contact layer 20, an n-type A cladding layer 40 is formed over the process conversion layer 31 , an active layer 50 is formed over the n-type cladding layer 40 , and a p-type cladding layer 60 is formed over the active layer 50 . The method for forming the light-emitting epitaxial structure 1 includes providing a growth substrate 10; then, on the growth substrate 10, a contact layer 20 is epitaxially grown by an organic metal chemical vapor deposition method. A lattice buffer layer (not shown) is grown between the contact layer 20 and the growth substrate 10 , wherein the lattice constant of the lattice buffer layer is between the contact layer 20 and the growth substrate 10 to improve epitaxial quality and reduce lattice defects. Conditions for the epitaxial growth of the contact layer 20 , for example, the reactor temperature is set at 900-1200° C.; the reactor pressure is set at 300-450 mbar; and the contact layer 20 is simultaneously doped with n. type dopant to between 1×10 17 ~1×10 18 cm -3 doping concentration. After the growth of the contact layer 20 is completed, the process conversion layer 31 and the n-type confinement layer 40 are successively grown; the n-type confinement layer 40 has an n-type dopant and a doping concentration. The growth conditions of the n-type tethered layer 40 and the contact layer 20 have process variations, or preferably have dramatic changes, so that film defects are generated when the n-type tethered layer 40 is directly grown on the contact layer 20 , resulting in reduced epitaxial quality. Therefore, the purpose of the process conversion layer 31 is to repair the defects of the process conversion layer 31 caused by the process variation of the growth conditions of the front and rear layers, thereby improving the epitaxial quality. In the definition of the present invention, the term "growth conditions" includes at least one process parameter set value selected from the group consisting of temperature, pressure and gas flow and other process parameter set values; "process variation" refers to the process The growth conditions of the layer before the conversion layer 31 are at least 3% different from the corresponding growth conditions of the latter layer; and "dramatic change" refers to the growth conditions of the layer before the process conversion layer 31, compared with the latter layer. The corresponding growth conditions of the layers are at least 10% different. For example, the set value of the reactor temperature of the n-type constrained layer 40 is between 700 and 1000°C; the set value of the reactor pressure is between 200 and 350 mbar, and at least one of the set value of the temperature or the set value of the pressure A difference of at least 3% from the corresponding set point for contact layer 20, or preferably at least 10%. The growth conditions of the process conversion layer 31 are approximately between the corresponding growth conditions of the contact layer 20 and the n-type tethered layer 40; preferably, they are close to the growth conditions of the n-type tethered layer 40; more preferably, they are the same as the growth of the n-type tethered layer 40. conditions; and the process conversion layer 31 has an n-type dopant and a doping concentration greater than one of the contact layer 20 and the n-type tethering layer 40, for example, the doping concentration is between 5×10 17 ~1×10 20 cm -3 Preferably, the doping concentration of the process conversion layer 31 is greater than the doping concentration of the contact layer 20 and the n-type binding layer 40, so that the conductivity of the process conversion layer 31 is greater than that of the contact layer 20 and/or the n-type binding layer 40. After the growth of the n-type constrained layer is completed, the active layer 50 and the p-type constrained layer 60 are successively grown to complete the light-emitting epitaxial structure of the light-emitting element.

[0032] figure 2 The second embodiment of the light-emitting epitaxial structure of the light-emitting element according to the present invention is disclosed. The light-emitting epitaxial structure 2 includes a growth substrate 10, a contact layer 20 formed on the growth substrate 10, an n-type confinement layer 40 formed on the contact layer 20, and the process The conversion layer 32 is formed on the n-type tie layer 40 , the active layer 50 is formed on the process conversion layer 32 , and the p-type tie layer 60 is formed on the active layer 50 . with the previous example ( figure 1) is that the process conversion layer 32 is formed between the n-type confinement layer 40 and the active layer 50 . The method of forming the light emitting epitaxial structure 2 includes first providing a growth substrate 10 . Next, the contact layer 20 is epitaxially grown on the growth substrate 10 by an organic metal chemical vapor deposition method. If the lattice constants of the contact layer 20 and the growth substrate 10 are different, a lattice buffer can be grown between the contact layer 20 and the growth substrate 10 layer (not shown), wherein the lattice constant of the lattice buffer layer is between the contact layer 20 and the growth substrate 10 to improve epitaxial quality and reduce lattice defects. After the growth of the contact layer 20 is completed, the n-type confinement layer 40 is successively grown; the n-type confinement layer 40 has an n-type dopant and a doping concentration. Conditions for the epitaxial growth of the n-type constrained layer 40 , for example, the reactor temperature is set at 700-1000° C.; the reactor pressure is set at 200-350 mbar; and the n-type constrained layer 40 is grown by doping simultaneously n-type dopant to between 1×10 17 ~5×10 18 cm -3 doping concentration. After the growth of the n-type tethered layer 40 is completed, the process conversion layer 32 and the active layer 50 are successively grown, wherein the n-type tethered layer 40 and the active layer 50 have process variations in the growth conditions, or preferably drastic variations, so that When the active layer 50 is directly grown on the n-type tethered layer 40, film defects are generated, resulting in a decrease in epitaxial quality. Therefore, the purpose of the process conversion layer 32 is to repair the defects caused by the variation of the growth conditions of the layers before and after the process conversion layer 32 , thereby improving the epitaxial quality. For example, the reactor temperature setting value of the active layer 50 is between 850 and 1100° C.; the reactor pressure setting value is between 200 and 350 mbar, and at least one of the temperature setting value or the pressure setting value is selected. The difference is at least 3%, or preferably at least 10%, from the corresponding set value for the n-type tethering layer 40 . The growth conditions of the process conversion layer 32 are approximately between the corresponding growth conditions of the n-type tethering layer 40 and the active layer 50 ; preferably, the growth conditions are close to those of the active layer 50 ; . The process conversion layer 32 has an n-type dopant and a dopant concentration greater than either of the n-type confinement layer 40 and the active layer 50 , for example, the dopant concentration is between 5×10 17 ~1×10 19 cm -3 Preferably, the doping concentration of the process conversion layer 32 is greater than that of the n-type binding layer 40 and the active layer 50, so that the conductivity of the process conversion layer 32 is greater than that of the n-type binding layer 40 and/or the active layer 50. After the growth of the active layer 50 is completed, the p-type confinement layer 60 is connected to complete the light-emitting epitaxial structure of the light-emitting element. The active layer structure includes a multiple quantum well structure to improve the internal quantum efficiency of the light-emitting element.

[0033] image 3 A third embodiment of the light-emitting epitaxial structure of the light-emitting element according to the present invention is disclosed. Compared with the aforementioned first and second embodiments, the difference lies in that the light-emitting epitaxial structure 3 also includes the same first process conversion layer as the first embodiment. 33 is formed between the contact layer 20 and the n-type confinement layer 40, and the second process conversion layer 34 is formed between the n-type confinement layer 40 and the active layer 50, which is the same as the second embodiment, so as to further improve the epitaxy of the light-emitting element. quality.

[0034] Figure 4 The first embodiment of the light-emitting element according to the present invention is disclosed. The light-emitting element 4 is a light-emitting epitaxial structure formed by image 3 The shown light-emitting epitaxial structure 3 is taken as an example, a plurality of light-emitting units separated from each other are formed from the substrate by a die process, such as the light-emitting units 4a and 4b shown in the figure, and the first electrodes 21 are respectively formed on the exposed surface. The contact layer 20 and the second electrode 61 are on the p-type confinement layer 60 . After the die process is completed, the growth substrate can be cut (as shown by dotted lines) to separate the light emitting units 4a and 4b to form individual light emitting elements. In another embodiment of the present invention, the light-emitting element further includes a contact layer formed between the second electrode and the p-type tethered layer to reduce the contact between the second electrode and the p-type tethered layer. or further comprising a current dispersing layer to make the current evenly distributed in the light emitting epitaxial structure.

[0035] For the light-emitting element formed according to the embodiment of the present invention, the size of the growth substrate is, for example, 10 mil×10 mil, under the condition of reverse bias voltage, at negative 10 microamps/mm 2 Under the current density of , the absolute value of the measured critical reverse voltage is at least 50 volts; and, under the condition of forward bias, at 150 mA/mm 2 It has a luminous efficiency of at least 50 lumens/watt when driven at a high current density. According to another embodiment of the present invention, the light-emitting element can obtain a better threshold reverse voltage, such as greater than 60 volts or, more preferably greater than 70 volts, by adjusting the growth stripe and doping concentration of the process conversion layer. , or most preferably greater than 100 volts.

[0036] Image 6 The voltage-current curve graph measured by the light-emitting element formed according to the embodiment of the present invention is disclosed. The light-emitting epitaxial structure of the light-emitting element of the present invention is under the condition of reverse bias voltage at negative 10 μA/mm 2 Under the current density of , the absolute value of the corresponding voltage value is about 102 volts (as shown by the dotted line; the value in the figure has been converted to a positive value); and under the condition of forward bias, at 150 mA/mm 2 When driven at a high current density, it can emit at least 50 lumens/watt of light. The light-emitting element of the present invention has both high threshold reverse voltage value and high luminance characteristics.

[0037] Figure 5 The tandem light-emitting element formed according to the embodiment of the present invention is disclosed, and the formation method of the tandem light-emitting element 5 is similar to Figure 4 In the illustrated embodiment, after the die process is completed, each light-emitting unit is electrically connected, such as Figure 5 As shown, a conductive layer 70 is formed between the first electrode of the light-emitting unit 4a and the second electrode of the light-emitting unit 4b so that the light-emitting units 4a and 4b form a light-emitting array structure connected in series. The light-emitting element 5 further includes an insulating layer 80 formed between the conductive layer 70 and the light-emitting units 4a and 4b and the substrate, so as to avoid short-circuiting the light-emitting element.

[0038] Figure 7A and 7B The AC light-emitting element according to the present invention is disclosed. The AC light-emitting element 7 is mainly used in an alternating current (AC) power supply, and includes a plurality of rectifying light-emitting array structures R1 to R4 and at least a direct-current light-emitting array structure E1 co-located on the growth substrate 10, each of the rectifier or DC light-emitting array structures is composed of Figure 5 As shown, it is composed of a plurality of light-emitting units connected in series, and the rectifier light-emitting array structures R1-R4 are electrically connected by the second connection layer 71 and the first-fourth wire pads 91-94 in the form of a Wheatstone bridge to form a rectifier structure. Please also refer to Figure 7B , the rectifying light-emitting array structure R1 is connected between the first wire pad 91 and the fourth wire pad 94; the rectifying light-emitting array structure R2 is connected between the first wire pad 91 and the second wire pad 92; the rectifying light-emitting array structure R3 is connected to Between the third wire pad 93 and the fourth wire pad 94; the rectifier light-emitting array structure R4 is connected between the second wire pad 92 and the third wire pad 93; the first wire pad 91 and the third wire pad 93 are respectively externally connected to AC The positive terminal and the negative terminal of the power supply are used to receive the AC voltage signal, and after being rectified by the rectifying light-emitting array structures R1 - R4 , the DC voltage signal is output on the second wire pad 92 and the fourth wire pad 94 . The DC light emitting array structure E1 is connected between the second wire pad 92 and the fourth wire pad 94 and receives the output DC voltage signal. During the positive half cycle of the AC voltage signal, the current flows through the light-emitting array structures R1, E1 and R4 of the AC light-emitting element 7 in sequence (such as Figure 7A In the negative half cycle of the AC voltage signal, the current flows through the light-emitting array structures R3, E1 and R2 of the AC light-emitting element 7 in sequence, and emits light; wherein the rectifying light-emitting array structure R1 ~R4 emits light during the half cycle of forward bias voltage, and the other half cycle is under reverse bias voltage and does not emit light, that is, the rectifier light-emitting arrays R1-R4 emit light in turn during the application of the AC signal; the DC light-emitting array structure E1, due to receiving The rectified DC voltage signal can emit light in both positive and negative half cycles.

[0039] The light-emitting unit formed by the embodiment of the present invention has a high critical reverse voltage value, which effectively improves the ability of the light-emitting unit to withstand reverse bias voltage, greatly reduces the number of light-emitting units in the rectified light-emitting array structure, and increases the The number of light-emitting units in the DC light-emitting array structure achieves the purpose of improving the light-emitting efficiency. Taking the AC power supply as an example with an AC frequency of 110V and 60 Hz, each light-emitting unit is, for example, a light-emitting epitaxial structure based on gallium nitride series and has the same area. Each light-emitting unit causes a voltage drop of about 3V (Voltage Drop). ) and the absolute value y of the critical reverse voltage value, the total number of light emitting cells (across different light emitting array structures) flowing through each positive or negative half cycle is about 37 to meet the 110V power supply. Each of the rectifying light-emitting array structures R1 to R4 has the same number m of light-emitting units, and the DC light-emitting array structure E1 has the number n of light-emitting units, then the number of light-emitting units of the DC light-emitting array structure E1 accounts for all the light-emitting elements. The ratio of the number of light-emitting cells is about n/(4m+n)×100%. During the forward half cycle, the potential difference of the rectifying light-emitting array structure R2 (in reverse bias) across the wire pads 91 and 92 should be the same as that of the rectifying light-emitting array structure R1 across the wire pads 91 and 92 and the DC light. The potential difference of the array structure E1 (both in forward bias) is the same as 3×(m+n) volts. In order to prevent the rectifier light-emitting array structure R2 under reverse bias from collapsing and failing, y must be greater than [3×(m +n)]/m at least 35 to avoid the variation of electrical operation and other external factors to make the component fail, that is, y must satisfy the following equation:

[0040] y 3 × ( m + n ) m + 35

[0041] The following table lists the combinations of the light-emitting array structures of the AC-type light-emitting elements formed according to the embodiments of the present invention:

[0042]

[0043] According to the exemplified combined embodiments, the proportion of the number of light-emitting units of the DC light-emitting array structure to the number of all the light-emitting units of the AC light-emitting element is at least greater than 50%, preferably greater than 60%, more preferably greater than 70%, or Greater than 80%, most preferably greater than 90% for better AC luminous efficiency embodiments. In another aspect of the present invention, the critical reverse voltage value of the light-emitting unit is at least greater than 50 volts, preferably greater than 60 volts, more preferably greater than 70 volts, most preferably greater than 100 volts, to improve the reliability of the light-emitting element. In another embodiment of the present invention, the area of ​​the light-emitting units of each of the rectifying light-emitting array structures is smaller than the area of ​​the light-emitting units of each of the DC light-emitting array structures, so as to further improve the reverse bias efficiency of the light-emitting element . In addition, except Figure 7A and Figure 7B The exemplified bridge-connected AC light-emitting element, the AC light-emitting element of the present invention may also include other connection types of AC light-emitting elements, such as an anti-parallel type, or other connection types of AC light-emitting elements element.

[0044] Figure 8 A light-emitting wafer according to the present invention is disclosed. The light-emitting wafer 8 includes a plurality of light-emitting units 81, and each light-emitting unit 81 has a light-emitting epitaxial structure, for example, the same as the Figure 4 Lighting unit 4a or 4b shown. Each light-emitting unit 81 is at minus 10 microamps/mm 2 has a critical reverse voltage at a current density of 150 mA/mm; 2When driven with a high current density, it has luminous efficiency; and, the average value of the absolute value of the critical reverse voltage of the plurality of light-emitting units 81 is at least greater than 50 volts, preferably greater than 60 volts, more preferably greater than 70 volts, most preferably greater than 100 volts; and the average value of the luminous efficiency of the plurality of light emitting units 81 is at least 50 lumens/watt. In another embodiment, the critical reverse voltage values ​​of the plurality of light-emitting units are distributed according to the size, and after deducting the absolute value of the critical reverse voltage value, which is located after 25% of the light-emitting units before and after the distribution, is located at The average value of the absolute value of the critical reverse voltage value of the remaining 50% of the light-emitting cells is at least greater than 50 volts, preferably greater than 60 volts, more preferably greater than 70 volts, most preferably greater than 100 volts; and under the condition of forward bias below 150 mA/mm 2 The average luminous efficiency of the remaining light-emitting cells located in the middle 50% is at least 50 lm/W when driven at a current density of 100%.

[0045] In the above embodiments, the materials of the contact layer, the n-type tethering layer, the process conversion layer, the p-type tethering layer and the active layer include III-V group compounds, such as gallium nitride series or gallium phosphide series materials. The growth substrate, for example, includes at least one material selected from the group consisting of sapphire, silicon carbide, gallium nitride, and aluminum nitride. The contact layer, the n-type tethered layer, the p-type tethered layer, and the active layer may have a single-layer or multi-layer structure, such as a superlattice structure. In addition, the light-emitting epitaxial structure of the present invention is not limited to growing on the growth substrate by a growth method, and other forming methods, such as direct bonding by bonding or bonding to a thermally conductive or conductive substrate through a medium, also fall within the scope of the present invention.