Minority-electron transport through atomic-diffusion-bonded InGaAs/a-Ge/InGaAs structure studied by photodiode characterization

We experimentally investigated minority-electron transport through a wafer-bonded InGaAs/a-Ge/InGaAs structure fabricated by using atomic-diffusion-bonding technology. The transport properties of minority electrons were examined in a uni-traveling-carrier photodiode (UTC-PD) structure. The C-V characteristics and the DC and O/E responses were compared with those of a conventional UTC-PD, which revealed that the bonded region behaved as an n-type semiconductor and the electric field was concentrated in the vicinity of the bonding interface when a bias voltage was applied to the PD. From the O/E response, it was found that the minority-electron transport through bonded region is similar to that in a conventional PD without wafer bonding under a relatively high bias condition.