Research On N-GaN Patterning And Its Influence On The Photoelectric Performance Of Ultraviolet LED

As humans continue to explore high-efficiency energy sources,Group III nitrides led by Ga N have entered the stage of history.Group III nitrides are more advantageous in manufacturing LEDs than traditional luminescent materials due to their large band gap,high electron mobility,and direct band gap.The research of Ga N-based LED in the field of visible light is very mature,but in the field of ultraviolet light,the luminous efficiency of Ga Nbased LED is still not affected by the internal quantum efficiency and light extraction efficiency.Ga N-based UV LEDs have the problem of poor crystalline quality.Defects in bulk materials can become non-radiative recombination centers,leading to a reduction in the quantum efficiency of the material.At the same time,the planar structure used for material growth is not conducive to the exit of light,resulting in a reduction in light extraction efficiency.Therefore,in this paper,silicon dioxide nanospheres are used as a mask,and ICP etching technology is used to obtain a patterned n-Ga N epitaxial wafer.The main purpose of the graphic processing is to subsequently grow uneven superlattices and quantum well structures on the etched holes to strengthen the local state of In Ga N,thereby enhancing the internal quantum efficiency;at the same time,such unevenness has a probability to increase the light exit,To improve light extraction efficiency.On the other hand,it is hoped that Ga N quantum dot materials will grow in the patterned holes,and the quantum efficiency of the quantum dots will increase the quantum efficiency of the material to improve the luminous efficiency.First,through the coating experiment of nanospheres,the optimal scheme was developed to produce the mask of silicon dioxide nanospheres,and the AFM and Raman characterization were performed after etching.The Ga N epitaxial thin film material grown up to the n-layer by MOCVD was studied on the surface of the n-Ga N epitaxial wafer under different coating methods,different particle diameters and different reagent dosages.cloth.Finally,it was found that the drift method 500 nm pellet solution and the isopropanol solution were prepared according to 1: 1 and 60 ul each with the densest arrangement of the pellets and the best quality of the silicon dioxide mask obtained.Then,the partially coated epitaxial wafer is etched to a depth of 6nm and 9nm.AFM can clearly observe the circular mesa structure.By comparing the E2(high)scattering peaks of the Raman spectrum,it was found that the etched stresses of 6nm and 9nm samples were reduced by 13.6% and 12.7%,respectively,compared to the samples without etching.Then,through the secondary growth of the etched experimental wafer and the standard wafer that has not been etched,the XRD,PL,and EL characterization comparison of the fullstructure epitaxial wafer is performed.The results are as follows.In the XRD test,the etched 6nm epitaxial wafer basically coincided with the standard sheet Ga N peak,superlattice peak,quantum well peak and In Ga N peak,and the peak position of the etched 9nm epitaxial wafer was shifted to the left by 0.01 °.It shows that the tiny etching of the N layer has no great effect on the phase of the material and the quality of the crystal.The experimental film is basically the same as the standard film,which achieves the expected effect of using nanospheres as a mask.The PL test and the EL test indicate that the etched wafer has a blue shift in the emission wavelength due to the enhancement of the In Ga N local state relative to the experimental wafer.At the same time,there may be quantum dot generation quantum size effect to strengthen this local state.The local effect of the top layer of the quantum well is weakened,and phase separation has occurred,but the crystal quality has been improved.Finally,the epitaxial wafers were made into 0810 specifications,and 300 samples were tested.The current,1m A,5m A and 20 m A,respectively,tested the wavelength,yield,voltage and luminous power of the three dies.Compared with the standard die,the wavelength of the 6nm etched n-Ga N surface is slightly red-shifted,the yield decreases,but the forward voltage decreases,and the luminous power increases by 0.2%-18.9%;the 9nm etched die wavelength The amount of red shift increases,the yield rate decreases,the forward voltage decreases,and the luminous power decreases by 0.9%-18.6%.It can be concluded from this that the use of Si O2 nanospheres as a mask to pattern the 6nm n-Ga N etching is beneficial to the reduction of UV LED forward voltage and the improvement of luminous efficiency.