Open AccessInfrared photoresponse of GeSn/n-Ge heterojunctions grown by molecular beam epitaxy
Author(s) -
Sang-Cheol Kim,
Nupur Bhargava,
Jay Prakash Gupta,
Matthew J. Coppinger,
J. Kolodzey
Publication year - 2014
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.22.011029
Subject(s) - photocurrent , molecular beam epitaxy , responsivity , materials science , heterojunction , optoelectronics , infrared , photodetector , photoconductivity , germanium , wavelength , optics , epitaxy , silicon , physics , nanotechnology , layer (electronics)
Heterojunction devices of Ge(1-x)Sn(x) / n-Ge were grown by solid source molecular beam epitaxy (MBE), and the mid-infrared (IR) photocurrent response was measured. With increasing Sn composition from 4% to 12%, the photocurrent spectra became red-shifted, suggesting that the bandgap of Ge(1-x)Sn(x) alloys was lowered compared to pure Ge. At a temperature of 100 K, the wavelengths of peak photocurrent were shifted from 1.42 µm for pure Ge (0% Sn) to 2.0 µm for 12% Sn. The bias dependence of the device response showed that the optimum reverse bias was > 0.5 volts for saturated photocurrent. The responsivity of the Ge(1-x)Sn(x) devices was estimated to be 0.17 A/W for 4% Sn. These results suggest that Ge(1-x)Sn(x) photodetectors may have practical applications in the near/mid IR wavelength regime.