Normal Incidence Mid-Infrared Photocurrent in AlGaN/GaN Quantum Well Infrared Photodetectors

Abstract

We report the growth and characterization of AlGaN/GaN multiple quantum well structures designed to have intersubband transitions in the mid-infrared region of the spectrum. The samples were nominally undoped but were found to contain a high electron population in the wells induced by the local polarization fields. The sample was characterized by the use of the Raman spectroscopy and photocurrent spectroscopy. The Raman spectroscopy shows electronic Raman scattering from intersubband transitions in the AlGaN/GaN quantum wells. The e 1 -e 2 and e 1 -e 3 transitions of the confined 2d electron population in the wells can clearly be observed. A sample designed to absorb at 4 µm was fabricated into mesa structures and the vertical photocurrent measured under normal incidence illumination from the free-electron laser FELIX. A wavelength and bias dependent photocurrent was observed in the mid-IR region of spectrum. The peak responsivity was of the order of 50 µA/W at 4 K, the photocurrent still being measurable at room temperature.

Room temperature operation of AlGaN/GaN quantum well infrared photodetectors at a 3–4 µm wavelength range

“…Applications for imaging QWIP devices in the 2-4 µm region of the spectrum include healthcare, firefighting and automobile safety, whilst single-channel detectors have applications in remote sensing and environmental monitoring [2,3]. Intersubband absorption has been measured in AlGaN/GaN quantum wells via absorption [4][5][6] and electronic Raman scattering (ERS) [7]. Near-infrared device operation at wavelengths as low as 1.55 µm has already been achieved in AlGaN/GaN-based QWIPs [8,9], and recently room temperature QWIP operation at 1.55 µm was reported [10].…”

Resonant tunneling effect in metal-semiconductor-metal ultraviolet detectors grown with AlGaN∕GaN multi-quantum-well interlayer

“…On the other hand, AlGaN / GaN MQW structures are found to be viable alternatives to meet the detector performance requirements. [5][6][7][8] III-nitride multiple-quantum-well ͑MQW͒ detectors were successfully demonstrated in the past. For example, Teke et al presented vertical geometry, backside illuminated, AlGaN / GaN MQW Schottky UV detectors, which had achieved nearly flat spectral response between 325 and 350 nm.…”