Mushroom Mesa Structure for InAlAs–InGaAs Avalanche Photodiodes

Mushroom mesa structure for InAlAs/InGaAs avalanche photodiodes (APD) was proposed and investigated. APD heterostructrures were grown by molecular-beam epitaxy. Fabricated APDs with the sensitive area diameter of about 30 micron were passivated by SiN deposition and demonstrated avalanche breakdown voltage Vbr 70–80 V. At the applied bias of 0.9 Vbr, the dark current was 75–200 nA. The single-mode coupled APDs demonstrated responsivity at a gain of unity higher than 0.5 A/W at 1550 nm.