Terahertz intersubband absorption in GaN/AlGaN step quantum wells

Abstract

International audienceWe demonstrate terahertz intersubband absorptions at frequencies of 2.1 THz (lambda approximate to 143 mu m) and 4.2 THz (lambda approximate to 70 mu m) in nitride-based semiconductor quantum wells. The structures consist of a 3 nm thick GaN well, an Al(0.05)Ga(0.95)N step barrier, and a 3 nm thick Al(0.1)Ga(0.9)N barrier. The absorption is detected at 4.7 K. The structure design has been optimized to approach a flat-band potential in the wells to allow for an intersubband absorption in the terahertz frequency range and to maximize the optical dipole moments. (C) 2010 American Institute of Physics. [doi:10.1063/1.3515423

Intersubband transitions in nonpolar GaN/Al(Ga)N heterostructures in the short- and mid-wavelength infrared regions

“…This quantum-confined Stark effect is a major hurdle for device design, although it has been partially compensated by the implementation of more complex step-QW designs. [9][10][11][12] The use of nonpolar a or m crystallographic orientations allows for GaN/Al(Ga)N systems to operate without the influence of this electric field 13 and facilitates the device design while still maintaining the benefits of GaN.…”

Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

“…[6][7][8][9][10] Spontaneous emission from c-plane AlGaN/GaN QCLs in the THz region has been reported, although full laser operation has remained elusive. 11 The built-in polarization fields in c-plane heterostructures place a lower limit on the transition energy, and the inherent asymmetry in the conduction band profile reduces the dipole moment at the larger well widths required for operation in the THz region.…”

“…These limitations have been partially mitigated by the implementation of more complex step-well designs. 9,12 However, the transition energies of these step-wells are highly sensitive to structural parameters. 13,14 Moreover, the additional layers significantly increase the complexity of design and growth of practical devices.…”

ABSORPTION COEFFICIENT IN A MQW INTERSUBBAND PHOTODETECTOR WITH NON-UNIFORM DOPING DENSITY & LAYER DISTRIBUTION

“…The impact of number of wells, doping density, applied bias and position of quasi-bound states on the operating wavelength and other performance parameters of the intersubband QWIPs have been reported by the researchers for multifarious applications [10][11][12][13]. The dark current, photocurrent and detectivity of the multiple well infrared detectors with asymmetric barrier layer and stepped well design have also been investigated [14][15][16]. However, according to the knowledge of the authors, the study of the absorption coefficient with non-uniformity in dimensional as well as structural parameters in multiple quantum well based optical receiver is not paid attention to so far.…”