Ultraviolet-to-infrared dual-band detectors based on quantum dot and heterojunction structures

Abstract

Tunneling quantum dot photodetector (T-QDIP) structures designed for multi-band infrared and heterojunction detectors for ultraviolet (UV) to infrared (IR) radiation detection are presented. In T-QDIPs, photoabsorption takes place in InGaAs QDs due to intersubband transitions of carriers. Photoexcited carriers are selectively collected through resonant tunneling, while the dark current is blocked by AlGaAs/InGaAs tunneling barriers. This approach to block dark current without reducing photocurrent was observed in a detector responding at ~ 6 and ~ 17 &mu;m up to 300 K. In addition, UV/IR dual-band detectors were developed based on GaN/AlGaN Heterojunction Interfacial Workfunction Internal Photoemission (HEIWIP) structures. A typical HEIWIP detector structure consists of a single (or series of) doped emitter(s) followed by an undoped barrier(s) between two highly doped contact layers. Reported UV/IR structures use <i>n</i>-doped GaN emitters and Al_xGa_1-xN barriers. The UV response is due to interband (valence-to-conduction) transitions in the undoped AlGaN barrier, while the IR response arises from intraband transitions in the n-doped GaN emitter. Preliminary detectors were successfully demonstrated with a 360 nm threshold UV response up to 300 K and 8-14 &mu;m IR response up to 80 K.