Near room temperature operation of a highly strained short wavelength (2.1 µm) AlAs/In0.84Ga0.16As/AlAs/InAlAs QWIP

Abstract

A strain-compensated AlAs/InxGa1−xAs/AlAs/InyAl1−yAs (x ≈ 0.8, y ≈ 0.5) quantum well infrared photodetector (QWIP) structure was grown by molecular beam epitaxy (MBE). Conditions of exact stoichiometric growth were applied at a temperature of ∼420 °C to produce structures capable of detecting IR radiation in the 2–5 µm mid-infrared spectrum. Double crystal x-ray diffraction (DCXRD) and room temperature photoluminescence (PL) experiments confirmed the excellent structural characteristics of the grown material system. A strong room temperature intersubband absorption peak was observed at a wavelength of 2.16 µm. Current–voltage (I–V) measurements as a function of temperature were carried out to electrically characterize the fabricated QWIP devices yielding devices working under background limited infrared photodetection (BLIP) conditions at 270 K. From the I–V curves, an activation energy of 270 meV at zero bias was extracted. This is in good agreement with a current transport mechanism which is dominated by thermionic emission. Photocurrent measurements were carried out and we demonstrate devices that are capable of working at a temperature as high as 270 K at a wavelength of 2.1 µm. The experimental results are in excellent agreement with the modelled values.