NiO/β-Ga2O3异质结紫外光电探测器的数值模拟研究

Numerical Simulation of NiO/β-Ga2O3 Heterojunction Ultraviolet Photodetectors

摘要:

β-Ga2O3因其高达4.8 eV的禁带宽度而成为日盲紫外光电探测器理想材料，但其p型导电性差的问题限制了性能。本论文中， 基于Sentaurus TCAD仿真软件构建了NiO/β-Ga2O3异质结，理论模拟对比分析了Ga?O?层均匀掺杂与梯度掺杂对异质结光电探测器性能的影响。结果发现梯度掺杂器件在254 nm紫外光照射下表现出更高的响应度（519 mA/W），相比于均匀掺杂（406 mA/W）提升28%，且其外量子效率（EQE）可达2.61%，暗电流密度由4.088×10?? A/cm2降低为1.204×10?11 A/cm2，结合不同光强下电场分布与能带结构图，我们认为梯度掺杂引起了空间电荷区扩展和内建电场的优化，减少了载流子复合概率，从而提升了光生载流子的分离与收集效率。梯度掺杂在优化载流子传输、抑制暗电流及提升响应速度方面具有显著潜力，为宽禁带半导体光电器件的开发提供了新思路。

Abstract:

β-Ga?O? has emerged as an ideal material for solar-blind ultraviolet photodetectors due to its ultra-wide bandgap of 4.8 eV, though its poor p-type conductivity restricts device performance. In this study, a NiO/β-Ga?O? heterojunction was constructed using Sentaurus TCAD simulations to comparatively analyze the effects of uniform doping versus gradient doping in Ga?O? layer on photodetector performance. Results demonstrate that the gradient-doped device achieves 28% higher responsivity (519 mA/W vs. 406 mA/W) under 254 nm illumination, along with enhanced external quantum efficiency (EQE) of 2.61%. Concurrently, the dark current density decreases significantly from 4.088×10?? A/cm2 to 1.204×10?11 A/cm2. Through electric field distribution and band structure analysis under varying light intensities, we propose that gradient doping induces expansion of space charge regions and optimization of built-in electric fields. These modifications reduce carrier recombination probability while improving separation and collection efficiency of photogenerated carriers. The gradient doping strategy demonstrates remarkable potential in optimizing carrier transport, suppressing dark current, and enhancing response speed, offering novel insights for developing wide-bandgap semiconductor optoelectronic devices.