Effects of polarization on intersubband transitions of Al_xGa_1−xN/GaN multi-quantum wells

Abstract

The effects of polarization and related structural parameters on the intersubband transitions of AlGaN/GaN multi-quantum wells (MQWs) have been investigated by solving the Schrödinger and the Poisson equations self-consistently. The results show that the intersubband absorption coefficient increases with increasing polarization while the transition wavelength decreases, which is not identical to the case of the interband transitions. Moreover, it suggests that the well width has a greater effect on the intersubband transitions than the barrier thickness, and the intersubband transition wavelength of the structure when doped in the barrier is shorter than that when doped in the well. It is found that the influences of the structural parameters differ for different electron subbands. The mechanisms responsible for these effects have been investigated in detail.

Double superlattice structure for improving the performance of ultraviolet light-emitting diodes

“…2(b), the lowest valence band effective barrier appears in sample B, which means that the introduction of polarization effect and interface stress can reduce the valence band barrier height of the single barrier layer. Moreover, due to the special energy band and polarization effect, [28] the AlGaN/GaN short-period superlattices in samples B and C generate periodic oscillation of the valence band, which will form a hole microstrip in the barrier layers. [29] The formation of the hole microstrip significantly reduces the ionization energy of the acceptor impurity.…”

A unified drain current 1/fnoise model for GaN-based high electron mobility transistors

“…[1] Low frequency noise (LFN) in HEMT is important since it becomes an important limitation of the device performances. These mechanisms originate either from trapping-detrapping processes in surface states and deep traps associated with material quality induced by piezoelectric polarization effects [2,3] or from permanent degradation induced by hot carrier interaction with trap sites occurring in the gatedrain region. [4] Although in as early as 1998, Balandin et al [5] measured the GaN-based HEMTs 1/ f noise.…”