基于金属掺杂ITO透明导电层的紫外LED制备

为降低ITO薄膜对紫外波段的光吸收，制备低电压高功率的紫外LED，研究了一种基于金属掺杂ITO透明导电层的365 nm紫外LED的制备工艺。利用1 cm厚的石英片生长了不同厚度ITO薄膜以及在ITO上掺杂不同金属的新型薄膜，并研究了在不同的退火条件下这种薄膜的电阻和透过率，分析了掺杂金属ITO薄膜的带隙变化。将这种掺杂的ITO薄膜生长在365 nm外延片上并完成电极生长，制备成14 mil×28 mil的正装LED芯片。利用电致发光（EL）设备对LED光电性能进行测试并对比。实验结果表明:掺Al金属的ITO薄膜能够相对ITO薄膜的带隙提高0.15 eV。在600℃退火后，方块电阻降低6.2 Ω/□，透过率在356 nm处达到90.8%。在120 mA注入电流下，365 nm LED的电压降低0.3 V，功率提高14.7%。ITO薄膜掺金属能够影响薄膜带隙，改变紫光LED光电性能。

Fabrication of UV LEDs with Metal-doped ITO Transparent Conductive Layer

In order to reduce the optical absorption of ITO thin films to UV waveband and to prepare low voltage as well as high power ultraviolet LEDs, the preparation process of 365 nm UV LED based on metal-doped ITO(Metal-ITO) transparent conductive layer was studied. The ITO thin films of different thickness and doped with different metals on ITO layer were grown by using 1 cm thickness quartz substrate, and the resistance and transmittance of the films were studied under different annealing conditions. The change of bandgap of Metal-ITO thin films was analyzed. Then, the Metal-ITO thin films were grown on 365 nm epitaxial wafers and completed the electrode growth, 14 mil×28 mil formal LEDs were prepared. Finally, the photoelectric properties of LED with Electroluminescence(EL) equipment were tested and compared. The experimental results show that the bandgap of Al-ITO thin film can be increased by 0.15 eV compared with that of ITO thin film. After annealing at 600℃, the square resistance is reduced by 6.2 Ω/□ and the transmittance is 90.8%. At 120 mA injection current, the decrease of voltage of 365 nm LED is 0.3 V and the increase of light output power is 14.7%. So, the Metal-ITO film can influence the bandgap of the film and along with the change of photoelectric performance of UV LED.