Highly strained InxGa(1-x)As-InyAl(1-y)As (x > 0.8, y < 0.3) layers for short wavelength QWIP and QCL structures grown by MBE

Highly strained quantum cascade laser (QCL) and quantum well infrared photodetector (QWIPs) structures based on InxGa((1-x))As-InyAl(1-y)As (x > 0.8, y < 0.3) layers have been grown by molecular beam epitaxy. Conditions of exact stoichiometric growth were used at a temperature of similar to420degreesC to produce structures that are suitable for both emission and detection in the 2-5 mum mid-infrared regime. High structural integrity, as assessed by double crystal X-ray diffraction, room temperature photoluminescence and electrical characteristics were observed. Strong room temperature intersubband absorption in highly tensile strained and strain-compensated In0.84Ga0.16As/AlAs/In0.52Al0.48As double barrier quantum wells gown on InP substrates is demonstrated. Gamma-Gamma intersubband transitions have been observed across a wide range of the mid-infrared spectrum (2-7 mum) in three structures of differing In0.84Ga0.16As well width (30, 45, and 80 Angstrom). We demonstrate short-wavelength IR, intersubband operation in both detection and emission for application in QC and QWIP structures. By pushing the InGaAs-InAlAs system to its ultimate limit, we have obtained the highest band offsets that are theoretically possible in this system both for the Gamma-Gamma bands and the Gamma-X bands, thereby opening up the way for both high power and high efficiency coupled with short-wavelength operation at room temperature. The versatility of this material system and technique in covering a wide range of the infrared spectrum is thus demonstrated. (C) 2003 Elsevier B.V. All rights reserved.