Title :
Improving the Performance of SiGe Metal–Semiconductor–Metal Photodetectors by Using an Amorphous Silicon Passivation Layer
Author :
Chen, Y.H. ; Hwang, J.D. ; Kung, C.Y. ; Chen, P.S. ; Wei, C.S. ; Wu, C.K. ; Liu, J.C.
Author_Institution :
Nat. Chung Hsing Univ., Taichung
Abstract :
SiGe metal-semiconductor-metal photodetectors (MSM-PDs) with a thin amorphous silicon (a-Si:H) passivation layer have been fabricated by an ultrahigh-vacuum chemical vapor deposition (UHVCVD) system. It was found that the thin (30 nm) a-Si:H passivation layer could effectively suppress the dark current of SiGe MSM-PDs. As compared to the unpassivated devices, the dark current for devices with a-Si:H passivation layers was drastically reduced by 1.7 times 105, and the photo-to-dark current ratio was enhanced by 1.33 times 106. We attribute this result to the passivation effect of a-Si:H films on SiGe surfaces by hydrogen diffusion, which can compensate the dangling bonds on the SiGe surface.
Keywords :
Ge-Si alloys; amorphous semiconductors; chemical vapour deposition; diffusion; elemental semiconductors; metal-semiconductor-metal structures; passivation; photodetectors; semiconductor materials; semiconductor thin films; Si:H - Surface; SiGe - Interface; SiGe MSM-PD; SiGe metal-semiconductor-metal photodetectors; UHVCVD system; a-Si:H passivation layer; dark current suppression; hydrogen diffusion; photo-to-dark current ratio; thin amorphous silicon passivation layer; ultrahigh-vacuum chemical vapor deposition; Amorphous silicon; Chemical vapor deposition; Dark current; FETs; Germanium silicon alloys; Materials science and technology; Optical surface waves; Passivation; Photodetectors; Silicon germanium; Amorphous silicon; SiGe; metal-semiconductor-metal; passivation; photodetector;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2007.909853
