Impact of hydrogenation on the minority carrier lifetime of InAsSbBi and the sensitivity of InAsSbBi <i>nBn</i> photodetectors

Abstract

InAsSb/InAsSbBi/InAsSb photoluminescence test structures and 4.32 μm cutoff InAsSbBi nBn photodetectors are examined before and after hydrogenation treatments with deuterium. Time-resolved photoluminescence is used to evaluate the minority carrier lifetime of both the test structures and the nBn photodetectors, while quantum efficiency and dark current are measured to evaluate the photodetectors’ sensitivity before and after hydrogenation. The post-growth hydrogenation process yields up to a 4× improvement in the minority carrier lifetime of the photoluminescence test structures, but no such lifetime increase is observed in the nBn photodetectors where the InAsSbBi active region is below the overlying AlGaAsSb barrier layer. The photodetectors exhibit a significant increase in their turn-on voltage following hydrogenation, but ultimately demonstrate the same sensitivity at their optimal operating bias, consistent with their identical minority carrier lifetime. Given that the increased lifetime in the photoluminescence test structures confirms that hydrogenation by deuterium is capable of passivating bulk defects within InAsSbBi, the minimal improvement in lifetime, operating sensitivity, and the shift in turn-on bias behavior of the nBn photodetectors suggest that the deuterium delivered by the process is not reaching the InAsSbBi active region. Secondary ion mass spectrometry confirms that the deuterium delivered by the hydrogenation process is trapped in the AlGaAsSb layer of the nBn.