Deep levels and low-frequency noise in AlGaAs∕GaAs heterostructures

Abstract

Low-frequency noise in AlGaN/GaN heterojunction field effect transistors on SiC and sapphire substratesThe low-frequency noise is studied in different AlGaAs/ GaAs heterostructures under electric biases as a function of the temperature. The heterostructures differ in the two-dimensional electron-gas density and the mobility. In addition to the thermal noise, different contributions are found and characterized ͑1/ f and generation-recombination noises͒. The presence of the generation-recombination noise is linked to defects in the interface between the channel and electrical contacts. Thermal activation energy values are deduced from Arrhenius plots and related to As Ga antisite defects and DX centers. The 1 / f noise is also characterized and its origin is identified as being the carrier mobility fluctuation dominated by lattice phonons.

Decomposition of1/fNoise inAlxGa1−xAs/GaAsHall Devices

“…Similar results on gated and ungated structures have been reported in Refs. [6,[9][10][11]15]. The generation-recombination noise spectra observed in these studies were not purely Lorentzian-type as expected for a single fluctuator but rather broadened spectra or superpositions of more than one Lorentzians on top of a large 1=f background.…”

“…Although, since the invention of Al x Ga 1ÿx As=GaAs heterostructures [4], there is a long history of noise studies of field effect transistor (FET), quantum point contact (QPC), and Hall-bar structures (see, e.g., Refs. [5][6][7][8][9][10][11][12][13][14][15][16]), no general understanding of the switching and 1=f noise phenomena in Al x Ga 1ÿx As= GaAs devices has been reached. In these studies various mechanisms of noise have been discussed (see below).…”

Observation of Thermally-Activated Electron Traps in GaAs/AlAs/GaAs Heterostructures in Low-Frequency Noise Measurements

“…It enables to calculate the thermal activation energy of the fluctuator to be E = 2.3 meV. This energy is very small in comparison with other observations basing on noise measurements in similar materials [10][11][12][13][14]. It is too small to be just related to Si shallow donor states either in GaAs or in AlAs.…”

GenerationRecombination

“…Table 1 summarizes technical description of the sample [3]. The samples are similar a HEMTs but without control gate or as a sheet resistance represented by a GaAs channel with a two-dimensional electron gas (2DEG).…”

“…The voltage noise was amplified by an EG&G 5004 low-frequency noise voltage amplifier, of which amplification was fixed to G = 10 3 , equivalent noise voltage of the order of 0.8 nV/√Hz, and equivalent noise current of 92 fA/√Hz at 1 kHz. Noise measurements were performed using a HP 35665A spectrum analyzer in the frequency range of 1 Hz -100 kHz [3]. The sample was mounted on a sample holder located at the end of a cryogenic cane that can be directly put in a helium reservoir.…”