InGaP/GaAs heterojunction phototransistors transferred to a Si substrate by metal wafer bonding combined with epitaxial lift-off.

We report fabrication and optical characteristics of an InGaP/GaAs heterojunction phototransistor (HPT) transferred to a Si substrate by a metal wafer bonding (MWB) and epitaxial lift-off (ELO) process at room temperature. An intermediate Pt/Au double layer between the HPT layer and Si provided a very smooth surface by which to achieve the MWB, and excellent durability against the acid solution during the ELO process. These processes were observed using scanning electron microscope (SEM) and atomic force microscopy (AFM). While the results on a low temperature photoluminescence (LTPL) signal and high resolution x-ray diffraction (HRXRD) rocking curve of the bonded device film implied a defect-free bonding, a very low collector dark current of the fabricated HPT was observed. The optical performance of a bonded InGaP/GaAs HPT on Si, operating at 635 nm wavelength is also investigated.