AlGaN异质结p-i-n型雪崩探测器

AlGaN Heterostructure Avalanche Photodetector

高增益AlGaN日盲雪崩探测器在国防安全与生命科学领域有重要的应用价值.本文通过引入Al_(0.2)Ga_(0.8)N/Al_(0.4)Ga_(0.6)N异质结设计,将雪崩电压从79.3 V降低到73 V,雪崩增益从1.9×10~6提高到4.8×10~6.通过数值模拟分析发现,异质界面极化电场与外加偏压方向一致,将高Al组分区域电场增强,从而降低了雪崩电压;虽然极化电场将低Al组分区域电场强度降低,但低Al组分区域离化系数大于高Al组分区域的离化系数约一个量级,空穴在高Al组分区域加速获得能量,在离化系数较高的低Al组分区域离化雪崩,提高了器件增益.

AlGaN solar-blind avalanche photodetectors could show potential applications in national defense safety and biological agent spectroscopy, because of the outstanding features such as lower operation voltages, lower power consumption, and a smaller device size. In particular, they could detect very weak solar blind light under intense background noise. Compared with conventional structure, the breakdown voltage of heterostructure AlGaN APDs can be reduced from 79.3 V to 73V, and the gain can be increased from1.9×106 to 4.8×106, which is mainly attributed to the polarization charges in the Al0.2Ga0.8N/Al0.4Ga0.6N interface. The polarization electric field enhances the electric field in high Al content layer, reducing the breakdown voltage obviously. The ionization efciency for the low Al content AlGaN region is larger by one magnitude than high Al content layer, so the holes accelerate in the high content region, and impact on low Al content layer. And the AlGaN Heterostructure avalanche photodetectors have low breakdown voltage and high gain.