TW201904087A - Light-emitting device and manufacturing metode thereof - Google Patents

Abstract

A light-emitting device includes a substrate; a first semiconductor layer on the substrate; a first barrier on the first semiconductor layer; a well on the first barrier including a first region having a first energy gap; and a second region having a second energy gap and being closer to the semiconductor layer than the first region; a second barrier on the well; and a second semiconductor layer on the second barrier; wherein the first energy gap decreases in a stacking direction of the light-emitting device and has a first gradient, the second energy gap increases in the stacked direction and has a second gradient, and an absolute value of the first gradient is less than an absolute value of the second gradient. Additionally, a method for manufacturing thereof is also provided.

Description

Light-emitting element and method of manufacturing same

The present invention relates to a light-emitting element, and more particularly to a light-emitting diode having a quantum well structure.

Compared with the traditional light source, the light-emitting diode has a longer service life, is lighter and thinner, and has better efficiency. It has been widely used in optical display devices, traffic signs, data storage devices, communication devices, lighting devices and medical equipment. In addition to being used alone, the light-emitting diode can be combined with other devices to form a light-emitting device, such as placing the light-emitting diode on the substrate and then connecting to one side of the carrier, or soldering or bonding. A material such as glue is formed between the carrier and the light emitting diode to form a light emitting device. In addition, the carrier may further comprise an electrode electrically connected to the LED.

In general, the light emitting diode includes an n-type semiconductor layer, an active region, and a p-type semiconductor layer. In order to improve the luminous efficiency of the light-emitting diode, a multiple quantum well structure can also be formed in the active region. How to improve the luminous efficiency by quantum well structure has become an important issue for improving the performance of light-emitting diodes.

The invention relates to a light-emitting element comprising: a substrate; a first semiconductor conductive layer formed on the substrate; a first barrier layer on the first semiconductor conductive layer; and a well layer on the first barrier layer The well layer includes: a first region having a first energy gap; and a second region having a second energy gap, and closer to the second semiconductor conductive layer than the first region; and a second barrier layer located at the well layer And a second semiconductor conductive layer formed on the second barrier layer; wherein the first energy gap decreases along a stacking direction of one of the light emitting elements and has a first gradient, and the second energy gap increases in the stacking direction and has a second gradient, and the absolute value of the first gradient is less than the absolute value of the second gradient.

The invention further relates to a method for fabricating a light-emitting device, comprising: forming a first semiconductor conductive layer on a substrate; forming a first barrier layer on the first semiconductor conductive layer; forming a well layer on the first barrier layer The step of forming a well layer includes: introducing, in a first time interval, a gallium-containing element gas, an indium-containing element gas, and a nitrogen-containing element gas at a first operating temperature to form a first a region; and in a second time interval, a gallium-containing element gas, an indium-containing element gas, and a nitrogen-containing element gas are introduced at a second operating temperature to form a second region, wherein the second time interval is later than the first a time interval; forming a second barrier layer on the well layer; and forming a second semiconductor conductive layer on the second barrier layer.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

The present invention will be described with reference to the drawings, in which the same or the same reference numerals are used in the drawings or the description, and in the drawings, the shape or thickness of the elements may be enlarged or reduced. It is to be noted that elements not shown or described in the figures may be in a form known to those skilled in the art.

Fig. 1A is a cross-sectional view showing a light-emitting element according to an embodiment of the present invention. The light-emitting element 1 includes a substrate 10, a nucleation layer 20, a lattice buffer layer 30, a first semiconductor conductive layer 40, a stress relief laminate 50, an active region 60, a second semiconductor conductive layer 70, a first electrode 80, and Two electrodes 90. In the present embodiment, the above-mentioned layers are grown on the substrate 10 in an epitaxial manner, and the growth direction thereof is represented by an arrow C _N , and the epitaxial method is, for example, a metal-organic chemical vapor deposition (metal-organic chemical vapor deposition). MOCVD) or molecular-beam epitaxy (MBE); the substrate 10 may be a single crystal substrate such as a conductive substrate or an insulating substrate; the conductive substrate is, for example, a germanium substrate, a gallium nitride substrate or a tantalum carbide (SiC). As the substrate, an insulating substrate such as a translucent sapphire substrate or the like can also be used. In the present embodiment, each layer is grown on the C-plane of the sapphire substrate by MOCVD epitaxy. In order to increase the light extraction rate, the surface of the substrate 10 may be etched to have a patterned surface on the epitaxial growth surface. Further, the growth sources of the three groups selected by the epitaxial crystal are, for example, trimethylgallium (TMGa), triethylgallium (TEGa), trimethylaluminum (TMAl), or trimethylindium (TMIn). The growth source of the five families is, for example, ammonia gas (NH ₃ ). The doping source is, for example, silane (SiH ₄ ) or bis-cyclopentadienyl magnesium (Cp ₂ Mg).

In order to reduce the lattice difference between the substrate 10 and the first semiconductor conductive layer 40 to reduce crystal defects, the core layer 20 and the lattice buffer layer 30 may be sequentially grown between the substrate 10 and the first semiconductor conductive layer 40. The thickness of both can be on the order of tens of nanometers (e.g., 30 nanometers) and several micrometers (e.g., 3 micrometers). The material of the nucleation layer 20 and the lattice buffer layer 30 is, for example, a tri-five material including a material such as gallium nitride (GaN) or aluminum nitride (AlN).

The first semiconductor conductive layer 40, for example, an n-type semiconductor conductive layer, is formed on the substrate 10, the nucleation layer 20, and the lattice buffer layer 30. In the present embodiment, the first semiconductor conductive layer 40 has a thickness of about several micrometers (for example, 2.5 um), a constituent material of gallium nitride, and a five-family growth source having a ratio of about 1000:1 (for example, Ammonia NH ₃ ) and a tri-family growth source (for example, trimethylgallium) to grow the first semiconducting layer 40, and further grow with decane as a doping source to form an antimony doped gallium nitride layer, but The constituent materials are not limited to this, but may be other three or five materials.

Similarly, in order to reduce the lattice difference between the first semiconductor conductive layer 40 and the active region 60 to reduce crystal defects, the stress relief layer 50 may also be formed on the first semiconductor conductive layer 40, and the stress relief layer 50 is, for example, a supercrystal. a lattice structure in which two semiconductor layers composed of different materials are overlapped with each other, and the two semiconductor layers are, for example, an indium gallium nitride layer (InGaN) and a gallium nitride layer, and have a thickness of about several hundred nanometers (for example, 120 nm), the stress relief layer 50 can also be composed of a semiconductor laminate composed of a plurality of layers of different materials having the same efficacy.

The active region 60 is grown after the stress relief layer 50 is formed. Please refer to FIG. 1B and FIG. 1C. FIG. 1B is a partial enlarged view of the active region 60 of FIG. 1A, and FIG. 1C is a partial front elevational view of FIG. 1B. In the present embodiment, the active region 60 is a multiple quantum well structure, but the invention is not limited thereto, and may be a single-layer quantum well structure in other embodiments. The active region 60 is formed by overlapping a plurality of well layers 601 and a plurality of barrier layers 603. In this embodiment, the barrier layer 603 is grown on the stress relief layer 50, and then the well layer 601 is grown, and then repeated. The barrier layer 603 and the well layer 601 are grown, and finally a barrier layer 603 or a well layer 601 is grown. The multiple quantum well structure of the active region 60 described above may also grow the well layer 601 first, then grow the barrier layer 603, and then repeat the overlap growth. Each well layer 601 has a thickness in the range of about a few nanometers (eg, 2 nanometers to 3 nanometers) and includes a region I 6010, a region II 6012, and a region III 6014. Wherein, the region I 6010 is closer to the first semiconductor conductive layer 40 and the stress relief layer 50, the region II 6012 is located between the region I 6010 and the region III 6014, and the region III 6014 is away from the first semiconductor conductive layer 40 and the stress relief layer 50. Farther. The material of the barrier layer 603 may be a three-five material, such as gallium nitride or aluminum nitride, and the material of the well layer 601 may also be a three-five material, such as In _x Ga _(1-x) N (nitriding). Indium gallium), Al _x Ga _(1-x) N (aluminum gallium nitride), Al _x In _y Ga _(1-xy) N (aluminum indium gallium nitride), Al _x In _1-x N ( Aluminum indium nitride) or a combination thereof, wherein 0 ≦ x, y, (1-xy) < 1. In this embodiment, the material of the barrier layer 603 is gallium nitride, and the material of the well layer 601 is indium gallium nitride. When the active region 60 is formed, the well layer 601 of the active region 60 can be grown through a five-member growth source (eg, ammonia gas) having a ratio of about 18,000:1 and a tri-generation growth source (eg, trimethylindium). The barrier layer 603 of the active region 60 is grown by a five-factor growth source (e.g., ammonia gas) having a ratio of about 2000:1 and a tri-generation growth source (e.g., triethylgallium), but the present invention is not limited to the above.

After the active region 60 is formed, a second semiconductor conductive layer 70 is formed on the active region 60. In this embodiment, the second semiconductor conductive layer 70 is, for example, a p-type semiconductor conductive layer, and the p-type semiconductor conductive layer may be a magnesium (Mg)-doped gallium nitride layer, but not limited thereto, and may be other Three or five family materials. In this embodiment, the fifth semiconductor growth layer 70 is grown by a five-member growth source having a ratio of about 5000:1 (for example, ammonia NH3) and a three-group growth source (for example, trimethylgallium), and dicyclopentan is used. The diene acts as a doping source for magnesium. After the second semiconductor layer 70 is formed, the first electrode 80 and the second electrode 90 are formed by a yellow light process, etching, metal deposition, or the like to complete the fabrication of the light-emitting element 1. The first semiconductor conductive layer 40 and the second semiconductor conductive layer 70 may be a single layer or a plurality of layers, or may be inserted into the first semiconductor conductive layer 40 or the second semiconductor conductive layer 70, respectively. Semiconductor layer.

Please refer to Figures 2A-2D for further understanding of the formation of active region 60. 2A is a flow rate versus time relationship between the well layer 601 and the barrier layer 603 according to the first embodiment of the present invention; FIG. 2B is a schematic view of the well layer 601 and the barrier layer 603 according to the first embodiment of the present invention; 2C is a temperature versus time diagram of the well layer 601 and the barrier layer 603 according to the first embodiment of the present invention; FIG. 2D is an energy band of the well layer 601 and the barrier layer 603 according to the first embodiment of the present invention. Structure comparison chart. As described above, the active region 60 is layered by a plurality of well layers 601 and a plurality of barrier layers 603 overlapping each other. As shown in FIGS. 2A-2D, the well layer 601 is located between the two barrier layers 603. When the barrier layer 603 is grown (only a portion of the region is shown), a gallium-containing gas is continuously introduced (for example, triethylgallium TEGa). ), an indium-containing gas (for example, trimethylindium TMIn), and a nitrogen-containing gas (for example, ammonia gas NH ₃ ), wherein the gallium-containing gas flow rate FR1, the indium-containing gas flow rate FR2, and the nitrogen-containing element The gas flow rate FR3 may each be maintained at a certain value, and the operating temperature is maintained at a first predetermined value T ₁ (for example, 870 degrees Celsius), and the barrier layer 603 is grown to a thickness of about several nanometers to several tens of nanometers ( For example 12 nm).

When the well layer 601 is formed, first, at the time of the growth time t ₁ to t ₂ (about 160 seconds), the flow rate of the gallium-containing element gas FR1, the flow rate of the indium-containing element gas FR2, and the flow rate of the nitrogen-containing element gas FR3 are the same. Each may be maintained at a value that gradually decreases from a first predetermined value T ₁ (eg, 870 degrees Celsius) to a second predetermined value T ₂ (eg, 755 degrees Celsius) to form region I 6010 of the formation 601. The above-described manner of changing the growth temperature includes a linear change, a step change, or another change. In general, when an epitaxial layer is formed by metal organic chemical vapor deposition, the indium content rises as the operating temperature decreases (or decreases as the operating temperature rises), by the above adjustment operation. The temperature can be gradually adjusted to the indium content of the region I 6010 such that the indium content of the region I 6010 is increased along the stacking direction of the light-emitting element 1 (the growth direction is indicated by the arrow _CN ), for example, increasing from GaN to In _0.25 Ga _0.75 N, but not limited to this. The way to increase can be linear, step change, or other changes.

After the formation of the region I 6010, the region II 6012 of the well layer 601 is grown at a time interval (about 60 seconds) from the growth time t ₂ to t ₃ , and the operating temperature can be maintained at the second predetermined value T ₂ . Further, the gallium-containing element gas flow rate FR1, the indium-containing element gas flow rate FR2, and the nitrogen-containing element gas flow rate FR3 may each be maintained at a constant value. Since the operating temperature is maintained at the second predetermined value T ₂ at this time, the indium content of the region II 6012 can be substantially regarded as a constant (for example, maintained at In _0.25 Ga _0.75 N).

After formation region and the region I 6010 II 6012, in the distance t to _{t. 3} (e.g. 60 seconds) well layer 601 is grown region III 6014, this time gallium-containing gas flow rate of FR1 _4, the indium element-containing gas flow rate The FR2 and the nitrogen-containing element gas flow rate FR3 are also each maintained at the above-mentioned fixed value, and the operating temperature is gradually increased from the second preset value T ₂ by a linear change, a step change, or other means to a third preset value T ₃ ( For example, 875 degrees Celsius), thereby gradually adjusting the indium content of the region III 6014, so that the indium content of the region III 6014 decreases along the stacking direction of the epitaxial crystal, for example, increasing from In _0.25 Ga _0.75 N to GaN, the decreasing manner can be It is a linear change or a step change. Moreover, for individual well layers 601, region III 6014 is closer to second semiconductor layer 70 than region I 6010, and region II 6012 is located between region I 6010 and region III 6014. That is, the region I 6010, the region II 6012, and the region III 6014 are sequentially formed. However, the order of formation of the region I, the region II, and the region III of the present invention is not limited to the above, and in other embodiments, the order of formation may also vary.

After forming the well layer 601, a barrier layer 603 is formed (only a partial region is illustrated), and the gallium-containing element gas is continuously supplied under the same gas flow conditions as the growth well layer 601 and the barrier layer 603 before the well layer ( For example, triethylgallium TEGa), an indium-containing gas (for example, trimethylindiumTMIn), and a nitrogen-containing gas (for example, ammonia NH ₃ ), and the operating temperature is maintained at a third preset value T. ₃ .

Further, as shown in FIG. 2D, the region I 6010 has an energy gap Eg _I (not shown in the drawing), and the energy gap Eg _{I is} along the stacking direction of the light-emitting element 1 (the normal direction of the C-plane of the substrate 10, with an arrow) C _N represents) decreasing linearly, stepwise, or otherwise, and having a first gradient (in the present embodiment, the first gradient is defined as the amount of change in energy gap per unit thickness in region I 6010 ΔEg _I /ΔD _I , wherein the thickness direction is parallel to the stacking direction C _N . In this embodiment, indium gallium nitride In _x Ga _(1-x) N is used as the well layer, and the energy gap Eg _{I is} decreased because the region I 6010 is formed. The operating temperature gradually decreases with the stacking direction, and the indium content increases as the temperature decreases (x becomes larger), thereby causing the energy gap Eg _{I to} decrease.

On the other hand, the region II 6012 has an energy gap Eg _II (not shown in the figure). Since the operating temperature is maintained at the second predetermined value T ₂ when the region II 6012 is formed, the indium content in the region II 6012 is substantially maintained, and the energy gap Eg _II can be regarded as a constant, in other words, the energy gap. The Eg _II does not have a gradient change along the stacking direction.

The region III 6014 has an energy gap Eg _III (not shown in the figure), and the energy gap Eg _III is increased in a linear, stepwise or other manner in the stacking direction (for the reason as described above) and has a second gradient. The second gradient G _III is defined as the amount of change in energy gap ΔEg _III /ΔD _III per unit thickness in the region III 6014. As can be seen from Fig. 2D, the amount of change in the energy gap Eg _I is smaller than the change in the energy gap Eg _III (only the change in value is considered), that is, the absolute value of the first gradient ∣ΔEg _I /ΔD _I ∣ is smaller than the absolute of the second gradient The value ∣ΔEg _III /ΔD _III ∣. This is because the operating temperature is decreased from the first preset value T ₁ to the second preset value T ₂ at a longer time t ₁ -t ₂ (for example, 160 seconds) in the growing region I 6010, and the corresponding influence The indium content in region I 6010 varies from a lower content to a higher content over a longer period of time (eg, 160 seconds), while the operating temperature in a growing region III 6014 is in a shorter t ₃ -t ₄ time interval. (for example, 60 seconds) rising from the second preset value T ₂ to the third preset value T ₃ , and the indium content in the corresponding influence region III 6014 is higher from the shorter time (for example, 60 seconds) Change to a lower level. Further, as shown in FIG. 2D, the average value of the energy gap Eg _I or the average value of the energy gap Eg _III is larger than the energy gap Eg _II , and the energy gap of the barrier layer 603 is also larger than the energy gap of the well layer 601.

In this embodiment, although the indium content is adjusted by the operating temperature, thereby changing the energy gap value of different regions in the well layer, the present invention is not limited to changing the operating temperature, and the gas to be introduced is not limited to the above. The adjusted metal content is also not limited to indium. In other embodiments, the metal content (for example, aluminum) in the well layer may also be adjusted by other means, thereby changing the energy gap value such that the absolute value of the first gradient ∣ΔEg _I /ΔD _I ∣ is smaller or larger than the first The absolute value of the two gradients ∣ΔEg _III /ΔD _III ∣. For example, if the material of the barrier layer is aluminum nitride AlN and the material of the well layer is aluminum gallium nitride Al _x Ga _(1-x) N layer, where 0≦x, (1-x)≦1, The gas that is introduced will include a gas containing aluminum. Since the energy gap of aluminum nitride AlN is about 6.1 eV, which is larger than 3.4 eV of gallium nitride GaN, in order to make the energy gap Eg _I of the region _I decrease with the stacking direction, and the energy gap Eg _III of the region III The rise in the stacking direction causes the aluminum content in the region I to decrease with the stacking direction, and the aluminum content in the region III increases with the stacking direction.

Please refer to FIGS. 3A-3D. FIG. 3A is a flow rate versus time relationship between a well layer and a barrier layer according to a second embodiment of the present invention; FIG. 3B is a view showing a well layer and a barrier according to a second embodiment of the present invention; FIG. 3C is a temperature versus time diagram of forming a well layer and a barrier layer according to a second embodiment of the present invention; FIG. 3D is an energy band and structure of a well layer and a barrier layer according to a second embodiment of the present invention; Comparison chart. The second embodiment of Figures 3A-3D is substantially similar to the first embodiment of Figures 2A-2D, with the main difference being the structure of the well layer in the active zone. In the second embodiment, the active region comprises a well layer 601' and a barrier layer 603', also in the region I 6010' where the well layer 601' is formed at a distance t ₁ -t ₂ , at t ₂ -t ₃ well layer 601 is formed from 'region II 6012', and the well layer 601 is formed in the time distance t ₃ -t ₄ in 'a region III 6014', wherein the region I 6010 'composed of GaN, for example, to increase from in _0.25 Ga The composition of _0.75 N, the region II 6012' is, for example, In _0.25 Ga _0.75 N, and the composition of the region III 6014' is, for example, increasing from In _0.25 Ga _0.75 N to GaN. The first embodiment is different from the second embodiment in that the t ₁ -t ₂ time interval (for example, 60 seconds) in the 3A to 3D map is shorter than the t ₃ -t ₄ time interval (for example, 160 seconds). Therefore, the amount of change in indium content per unit time in the distance t ₁ -t ₂ is larger than the amount of change in indium content per unit time in the t ₃ -t ₄ time interval (only values are considered). Therefore, as shown in Fig. 3D, the energy gap Eg _{I '} of the region I 6010' varies with the thickness D _{I '} compared with the energy gap E g _{III '} of the region III 6014 _' with the thickness D _{III '} (Only consider the value of the size). In other words, the second embodiment of the absolute value of the first gradient _{|ΔEg I '/} ΔD I'| an absolute value greater than the second gradient _{|ΔEg III'} / ΔD III'|.

The durations of the t ₁ -t ₂ time interval, the t ₂ -t ₃ time interval, and the t ₃ -t ₄ time interval in the first embodiment and the second embodiment of the present invention are not limited to 160 seconds, 60 seconds, 60 degrees. Seconds are 60 seconds, 60 seconds, 160 seconds. In other embodiments, in order to change the indium content of each time interval, the duration of different time intervals may be changed correspondingly. For example, the time interval of t ₁ -t ₂ may be 2 to 3 times of the distance of t ₃ -t ₄ , or the time interval of t ₁ -t ₂ is shorter than the distance of t ₃ -t ₄ , or is t ₃ - The t ₄ time interval and the t ₂ -t ₃ time interval are longer than the t ₁ -t ₂ time interval. The present invention is not limited to the above, and only needs to change the difference (absolute value) of the temperature per unit time between the time interval of t ₁ -t _{2 and the} time interval of t ₃ -t ₄ , thereby correspondingly making the region I and the region The absolute value of the amount of change (gradient) of indium content per unit thickness of III is different. In addition, the first preset value, the second preset value, and the third preset value are not limited to 870 degrees Celsius, 755 degrees Celsius, and 875 degrees Celsius, and the first preset value and the third preset value are greater than the second value. The default value is fine. In other embodiments, the first preset value and the third preset value may also be set in the vicinity of 900 degrees Celsius, and the second preset value is less than 900 degrees Celsius. In addition, in other embodiments, the first preset value may be between 870 degrees Celsius and 900 degrees Celsius, the second preset value may be between 750 degrees Celsius and 780 degrees Celsius, and the third preset value may be between 870 degrees Celsius and Celsius. Between 900 degrees Celsius.

Referring to FIG. 4, FIG. 4 is a view showing the energy layer of the well layer and the barrier layer of the light-emitting element and the conventional light-emitting element according to the first embodiment and the second embodiment of the present invention. In FIG. 4, S indicates a conventional one. A light-emitting element, G denotes a light-emitting element of the first embodiment of the present invention, and N denotes a light-emitting element of the second embodiment of the present invention. In FIG. 4, the materials of the well layer S01 and the barrier layer S03 of the conventional light-emitting element S are respectively indium gallium nitride In _0.25 Ga _0.75 N and gallium nitride GaN, and the energy gap of the well layer S01 is a fixed value. It does not change with thickness.

Referring to Fig. 5, Fig. 5 is a diagram showing the relationship between the internal quantum efficiency and the power of the light-emitting element according to the first embodiment and the second embodiment of the present invention and the conventional light-emitting element of Fig. 4. In Fig. 5, S denotes a conventional light-emitting element in Fig. 4, and A denotes a light-emitting element (A and G and N at the same time) according to the first embodiment and the second embodiment of the present invention, which is clear from Fig. 5. It is seen that the internal quantum efficiency of the light-emitting element according to the first embodiment of the present invention and the second embodiment is higher than the internal quantum efficiency of the conventional light-emitting element at the same power.

Please refer to FIGS. 6A-6B. FIG. 6A is a diagram showing relationship between output power and current density of the light-emitting element according to the first embodiment and the second embodiment of the present invention, and FIG. 6B is a first embodiment of the present invention. And the relationship between the normalized efficiency and the current density of the light-emitting element of the second embodiment and the conventional light-emitting element. In the figure, S denotes a conventional light-emitting element, G denotes a light-emitting element according to a first embodiment of the present invention, and N denotes a light-emitting element according to a second embodiment of the present invention. Figure 6A shows the results of the measurement of the light-emitting element at room temperature, and Figure 6B normalizes the measurement results with the output power of each element at a low temperature to obtain a light-emitting element. The trend of efficiency increases with current density. As shown in FIG. 6A, the output powers of the first embodiment and the second embodiment and the conventional light-emitting elements are 136.8 mW and 122.7 mW, respectively, under the same operating voltage and current density of 69 A/cm ² . At 110.1 mW, the output power of the light-emitting elements of the first embodiment and the second embodiment was increased by 24.3% and 11.4%, respectively, compared to the conventional light-emitting elements. 6B shows that the illuminating element of the first embodiment of the present invention and the conventional illuminating element have a normalized efficiency of 73% and 61% under the condition of a current density of 69 A/cm ² , that is, the first embodiment. The light-emitting elements increase in efficiency with increasing current density compared to conventional light-emitting elements.

Further, the external quantum efficiency (not shown) of the conventional light-emitting element, the first embodiment, and the second embodiment light-emitting element was 59.6%, 68.3%, and 66.5, respectively, under the condition of a current density of 13.8 A/cm ² . %, and the output power values of the light-emitting elements of the second embodiment of the first embodiment are increased by 11.7% and 5.8%, respectively, compared to the conventional light-emitting elements. It can be seen from the above that the light-emitting elements of the first embodiment and the second embodiment of the present invention have higher output than the conventional light-emitting elements, regardless of the current density of 69 A/cm ² or 13.8 A/cm ² . Power and high luminous efficiency.

See Figures 7A, 8A, and 9A for simulation results with applied bias. FIG. 7A is a diagram showing a carrier concentration, an energy band and a positional relationship between a well layer and a barrier layer of a conventional light-emitting element; FIG. 8A is a carrier of the well layer 601 and the barrier layer 603 according to the first embodiment of the present invention; Concentration, energy band and positional relationship diagram; FIG. 9A is a diagram showing carrier concentration, energy band and position relationship of the well layer 601' and the barrier layer 603' according to the second embodiment of the present invention. For the sake of clarity, in the figures 7A, 8A, and 9A, the structural codes corresponding to the positions (ie, barrier layer, well layer, region I, region II, and region III) are respectively indicated above the plane. It can be seen from the figures 7A, 8A, and 9A that a higher carrier concentration occurs at the well layer, and the peaks of the electron concentrations of the first embodiment and the second embodiment of the present invention are compared with the conventional light-emitting elements. The position of the peak of the hole concentration is relatively close. The meaning of this represents that the wave functions of electrons and holes in space overlap, and the recombination rate is better than that of the conventional light-emitting elements. In addition, as shown in FIG. 8A, the change of the energy gap is moderate in the region I 6010 of the well layer 601 and is relatively intense in the region III 6014. When the light-emitting element of the first embodiment of the present invention is actuated, the electrons are from the region I 6010. Zone III 6014 moves, and the hole moves from zone III 6014 to zone I 6010. This design accelerates the movement of the hole to increase efficiency and effectively limits electron movement to improve the condition of electronic overflow.

Please refer to Figures 7B, 8B, and 9B, which are simulation results under an applied bias voltage. FIG. 7B is a well layer and a barrier layer energy band and a Fermi energy diagram of a conventional light-emitting element; FIG. 8B is a view showing a well layer and a barrier layer energy band and a Fermi energy level diagram according to the first embodiment of the present invention; FIG. 9B is a diagram showing the energy band and Fermi energy level of the well layer and the barrier layer according to the second embodiment of the present invention. In the 7B, 8B, and 9B diagrams, there are four line segments. The upper solid line and the broken line respectively indicate the Fermi level of the conduction band and the electron, and the lower solid line and the broken line respectively indicate the Fermi level of the valence band and the hole. . Compared with Figure 7B, the Fermi level of the electron in Figure 8B is farther away from the minimum value (valley) of the conduction band, which means that the probability of electrons appearing in the well 601 is higher than that of the electron in the well S01, and The area enclosed by the rice energy level and the conduction band is large (as indicated by the diagonal line), which means that the number of electrons is also larger in the well layer 601.

Referring to FIG. 10, FIG. 10 is a diagram showing the relationship between the recombination rate and the positional simulation of the light-emitting element and the conventional light-emitting element according to the first embodiment and the second embodiment of the present invention. S, G, and N respectively represent a conventional light-emitting element and the light-emitting elements of the first embodiment and the second embodiment. As shown in FIG. 10, in the light-emitting elements of the first embodiment and the second embodiment of the present invention, the recombination rate of the active region is better than that of the conventional active region.

Referring to FIG. 11, FIG. 11 is a diagram showing the relationship between the normalized efficiency and the current density of the light-emitting element according to the first embodiment of the present invention and the conventional light-emitting element. S and G respectively represent a conventional light-emitting element having no polarization electric field and the light-emitting element of the first embodiment. SP and GP respectively represent a conventional light-emitting element in the case of a polarized electric field (0.7 M volt ̇ cm ^-1 ) and a light-emitting element of the first embodiment of the present invention. As can be seen from the figure, the light-emitting element of the first embodiment of the present invention has a lower degree of efficiency degradation than that of the conventional light-emitting element, with or without the polarization of the polarization electric field.

Although the invention has been described above, it is not intended to limit the scope of the invention, the order of implementation, or the materials and process methods used. Various modifications and variations of the present invention are possible without departing from the spirit and scope of the invention.

1‧‧‧Lighting elements

10‧‧‧Substrate

20‧‧‧Nuclear layer

30‧‧‧ lattice buffer layer

40‧‧‧First semiconductor conductive layer

50‧‧‧stress release layer

60‧‧‧active area

601, 601', S01‧‧‧ wells

603, 603', S03‧‧ ‧ barrier layer

6010, 6010’‧‧‧ Area I

6012, 6012'‧‧‧Regional II

6014, 6014'‧‧‧Regional III

70‧‧‧Second semiconductor conductive layer

80‧‧‧first electrode

90‧‧‧second electrode

S‧‧‧Study light-emitting elements

S-P‧‧‧Looking light-emitting elements under polarization

G‧‧‧First embodiment light-emitting element

G-P‧‧‧Lighting element of the first embodiment under polarization

N‧‧‧Second embodiment light-emitting element

t ₁ , t ₂ , t ₃ ‧‧‧ time

T ₁ , T ₂ , T ₃ ‧‧‧ Preset (temperature)

FR1, FR2, FR3‧‧‧ flow

C _N ‧‧‧Growth direction

Fig. 1A is a cross-sectional view showing a light-emitting element according to an embodiment of the present invention.

Fig. 1B is a partial enlarged view of Fig. 1A.

Fig. 1C is a partial front elevational view of Fig. 1B.

Fig. 2A is a diagram showing the relationship between flow rate and time when forming a well layer and a barrier layer according to the first embodiment of the present invention.

2B is a schematic view of a well layer and a barrier layer according to a first embodiment of the present invention.

Fig. 2C is a graph showing temperature versus time for forming a well layer and a barrier layer according to the first embodiment of the present invention.

2D is a comparison diagram of the energy band and structure of the well layer and the barrier layer according to the first embodiment of the present invention.

Fig. 3A is a diagram showing the relationship between flow rate and time when forming a well layer and a barrier layer according to a second embodiment of the present invention.

3B is a schematic view of a well layer and a barrier layer according to a second embodiment of the present invention.

Fig. 3C is a graph showing temperature versus time for forming a well layer and a barrier layer according to a second embodiment of the present invention.

Fig. 3D is a view showing the energy band and structure of the well layer and the barrier layer according to the second embodiment of the present invention.

Figure 4 is a view showing the energy layer of the well layer and the barrier layer of the light-emitting element of the first embodiment and the second embodiment of the present invention and the conventional light-emitting element.

Fig. 5 is a graph showing the relationship between the internal quantum efficiency and the power of the light-emitting element of the first embodiment and the second embodiment of the present invention and the conventional light-emitting element.

Fig. 6A is a graph showing the relationship between the output power and the current density of the light-emitting element of the first embodiment and the second embodiment of the present invention and the conventional light-emitting element.

Fig. 6B is a graph showing the relationship between the normalized efficiency and the current density of the light-emitting element of the first embodiment and the second embodiment of the present invention and the conventional light-emitting element.

Fig. 7A is a diagram showing the relationship between the carrier concentration, the energy band and the position of the well layer and the barrier layer of the conventional light-emitting element.

Figure 7B is a well layer and barrier layer energy band and Fermi energy diagram of a conventional light-emitting element.

Fig. 8A is a diagram showing the relationship between the carrier concentration, the energy band and the position of the well layer and the barrier layer according to the first embodiment of the present invention.

Figure 8B is a diagram showing the energy band and Fermi energy level of the well layer and the barrier layer according to the first embodiment of the present invention.

Fig. 9A is a diagram showing the relationship between the carrier concentration, the energy band and the position of the well layer and the barrier layer according to the second embodiment of the present invention.

Figure 9B is a diagram showing the energy band and Fermi energy level of the well layer and the barrier layer according to the second embodiment of the present invention.

Fig. 10 is a diagram showing the relationship between the recombination ratio and the positional simulation of the light-emitting element of the first embodiment and the second embodiment of the present invention and the conventional light-emitting element.

Fig. 11 is a graph showing the relationship between the normalization efficiency and the current density of the light-emitting element and the conventional light-emitting element according to the first embodiment of the present invention.

no.

Claims (10)

A light-emitting element comprising: a substrate; a first semiconductor conductive layer on the substrate; a first barrier layer on the first semiconductor conductive layer; a well layer on the first barrier layer, The well layer includes a first region having a first energy gap and a second region having a second energy gap, and the first region is closer to the first semiconductor conductive layer than the second region; a barrier layer on the well layer; and a second semiconductor conductive layer on the second barrier layer; wherein the first energy gap decreases along a stacking direction of the light emitting element and has a first gradient, the first The two energy gaps are incremented in the stacking direction and have a second gradient, and the absolute value of the first gradient is greater than the absolute value of the second gradient. The light-emitting element of claim 1, wherein the first region comprises indium, and the indium content of the first region is increased along the stacking direction. The light-emitting element of claim 1, wherein the second region comprises indium, and the indium content of the second region decreases along the stacking direction. The illuminating element of claim 1, further comprising a third region between the first region and the second region, wherein the third region has a third energy gap, the third energy The gap does not have a gradient change along the stacking direction. The light-emitting element of claim 4, wherein the third region comprises indium, and the indium content of the third region is a constant. The illuminating element of claim 1, wherein the first barrier layer has an energy gap, the second barrier layer has an energy gap, and a maximum value of the first energy gap is substantially The energy gap of the first barrier layer is the same, or a maximum of the second energy gap is substantially the same as the energy gap of the second barrier layer. The light-emitting element according to claim 1, wherein the first energy gap is decreased in the stacking direction by a linear change or a step change. The illuminating element of claim 1, wherein the second energy gap increases in the stacking direction by a linear change or a step change. The light-emitting element of claim 1, wherein the first region comprises aluminum, and the aluminum content of the first region decreases along the stacking direction. The light-emitting element of claim 1, wherein the second region comprises aluminum, and the aluminum content of the second region is increased along the stacking direction.