Supported by the National Natural Science Foundation of China under Grant Nos 11574362,61210014,11374340 and 11474205;the Innovative Clean-Energy Research and Application Program of Beijing Municipal Science and Technology Commission under Grant No Z151100003515001;the National Key Technology R&D Program of China under Grant No 2016YFB0400302
Heterojunction phototransistors(HPTs)with scaling emitters have a higher optical gain compared to HPTs with normal emitters.However,to quantitatively describe the relationship between the emitter-absorber area ratio(A...