Design and fabrication of InAs/GaAs quantum-dot resonant-cavity avalanche photodetectors

InAs/GaAs quantum dot (QD) resonant-cavity avalanche photodetectors (RC-APD) operating at 1 μm were designed and fabricated. The structure of RC-APD was designed such that it would resonate with the light incident from the top mesa. The RC-APD was grown by solid-source molecular-beam epitaxy on a semi-insulating GaAs substrate. The area of the top mesa was 10 × 10 μm2 and the absorbing region consisted of a 2.1 monolayer (ML) InAs QD layer sandwiched by two 75.5 nm-thick GaAs spacers. One of the RC-APDs exhibited a large gain factor M ∼100 and a low dark current of ∼10 nA at a breakdown voltage of ∼20 V.