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To enhance the avalanche ionization, we designed a new separate absorption and multiplication AlGaN solarblind avalanche photodiode(APD) by using a high/low-Al-content AlGaN heterostructure as the multiplication region instead of the conventional AlGaN homogeneous layer. The calculated results show that the designed APD with Al_(0.3)Ga_(0.7)N/Al_(0.45)Ga_(0.55)N heterostructure multiplication region exhibits a 60% higher gain than the conventional APD and a smaller avalanche breakdown voltage due to the use of the low-Al-content Al_(0.3)Ga_(0.7)N which has about a six times higher hole ionization coefficient than the high-Al-content Al_(0.45)Ga_(0.55)N. Meanwhile, the designed APD still remains a good solar-blind characteristic by introducing a quarter-wave AlGaN/AlN distributed Bragg reflectors structure at the bottom of the device.
To enhance the avalanche ionization, we designed a new separate absorption and multiplication of AlGaN solarblind avalanche photodiode (APD) by using a high / low-Al-content AlGaN heterostructure as the multiplication region instead of the conventional AlGaN homogeneous layer. The calculated results show that the designed APD with Al 0.3 Ga 0.7 N / Al 0.45 Ga 0.55 N heterostructure multiplication region exhibits a 60% higher gain than the conventional APD and a smaller avalanche breakdown voltage due to the use of the low- Al-content Al_ (0.3) Ga_ (0.7) N which has about a six times higher hole ionization coefficient than the high-Al_content Al_ (0.45) Ga_ (0.55) blind characteristic by introducing a quarter-wave AlGaN / AlN distributed Bragg reflectors structure at the bottom of the device.