Zhang Lingxia, Wu Hualong, He Chenguang, Zhang Kang, Liu Yunzhou, Wang Qiao, He Longfei, Zhao Wei, Chen Zhitao
School of Physics, Electronics and Intelligent Manufacturing, Huaihua University, Huaihua 418000, China.
Institute of Semiconductors, Guangdong Academy of Sciences, Guangzhou 510650, China.
Micromachines (Basel). 2024 Jun 13;15(6):778. doi: 10.3390/mi15060778.
This research explores the architecture and efficacy of GaN/AlGaN-based heterojunction phototransistors (HPTs) engineered with both a compositionally graded and a doping-graded base. Employing theoretical analysis along with empirical fabrication techniques, HPTs configured with an aluminum compositionally graded base were observed to exhibit a substantial enhancement in current gain. Specifically, theoretical models predicted a 12-fold increase, while experimental evaluations revealed an even more pronounced improvement of approximately 27.9 times compared to conventional GaN base structures. Similarly, HPTs incorporating a doping-graded base demonstrated significant gains, with theoretical predictions indicating a doubling of current gain and experimental assessments showing a 6.1-fold increase. The doping-graded base implements a strategic modulation of hole concentration, ranging from 3.8 × 10 cm at the base-emitter interface to 3.8 × 10 cm at the base-collector junction. This controlled gradation markedly contributes to the observed enhancements in current gain. The principal mechanism driving these improvements is identified as the increased electron drift within the base, propelled by the intrinsic electric field inherent to both the compositionally and doping-graded structures. These results highlight the potential of such graded base designs in enhancing the performance of GaN/AlGaN HPTs and provide crucial insights for the advancement of future phototransistor technologies.
本研究探索了基于GaN/AlGaN的异质结光电晶体管（HPT）的结构和功效，这些晶体管采用了成分渐变和掺杂渐变的基区设计。通过理论分析和实证制造技术，观察到配置有铝成分渐变基区的HPT的电流增益有显著提高。具体而言，理论模型预测电流增益将增加12倍，而实验评估显示，与传统的GaN基区结构相比，增益提高更为显著，约为27.9倍。同样，采用掺杂渐变基区的HPT也显示出显著的增益，理论预测表明电流增益翻倍，实验评估显示增加了6.1倍。掺杂渐变基区实现了空穴浓度的策略性调制，从基极-发射极界面处的3.8×10¹⁷ cm⁻³到基极-集电极结处的3.8×10¹⁵ cm⁻³。这种受控的渐变显著促进了观察到的电流增益的提高。推动这些改进的主要机制被确定为基区内电子漂移的增加，这是由成分渐变和掺杂渐变结构固有的内建电场推动的。这些结果突出了这种渐变基区设计在提高GaN/AlGaN HPT性能方面的潜力，并为未来光电晶体管技术的发展提供了关键见解。
