Dark current reduction in nano-avalanche photodiodes by incorporating multiple quantum barriers

Multiple quantum barriers have been used to suppress the dark current of nanoscale avalanche photodiodes (APDs). The n⁺–π–p⁺-structured Si–3C-SiC heterojunction-based multiple quantum barrier (MQB) APDs are considered and a detailed model of dark current has been developed from the self-consistent solution of the coupled Schrödinger–Poisson equations. Four major types of electron–hole pair (EHP) generation mechanisms such as (1) thermal generation, (2) band-to-band tunnelling generation, (3) trap-assisted tunnelling generation and (4) avalanche generation are considered for calculating variation of the total dark current with reverse bias voltage. It is observed that the dark current can be suppressed significantly by increasing both the number and thickness of quantum barriers. However, the authors have also admitted that both the number and thickness of quantum barriers cannot be increased indefinitely, since it will cause deterioration in spectral response of the device in near-infrared range (λ < 1100 nm).