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 sensitive area diameter of about 30 micron were passivated by SiN deposition and demonstrate avalanche breakdown voltage Vbr $\sim$70–80 V. At applied bias of 0.9 Vbr the dark current was $\sim$75–200 nA. The single-mode coupled APDs demonstrate responsivity at a gain of unity is high than 0.5A/W at 1550 nm.