Optoelectrical Characterizations of GeSn Heterojunction Photodiodes with 6% to 16% of Sn

We study vertical GeSn p-i-n heterostructures grown by RP-CVD on GeSn step-graded buffers with Sn content ranging from 6% to 16%. The performed spectrally-resolved photocurrent measurements allowed us to determine the direct or indirect bandgap behaviour of our devices. We report on the electrical and optical behavior of the fabricated photodiodes at room temperature.