Multicolor photodetector based on GaAs quantum rings grown by droplet epitaxy

Abstract

Photoresponse from multicolor photodetector was measured in the spectral range of $0.4–6.0\mu \mathrm{m}$ as a function of temperature and bias voltage. Devices were fabricated from wafers with an active region of five periods of GaAs quantum rings grown by droplet epitaxy technique on lattice matched ${\mathrm{Al}}_{0.3}{\mathrm{Ga}}_{0.7}\mathrm{As}$ barriers. The photoresponse spectra exhibit two broad bands in the visible-near-infrared and midinfrared spectral regions. The visible-near-infrared band, which is due to interband transitions, was observed at temperatures as high as room temperature. On the other hand, the midinfrared band, which is due to intersubband transitions, was observed at temperature lower than $80\mathrm{K}$ .