The growth and physics of ultra-high-mobility two-dimensional hole gas on (311) A GaAs surface (original) (raw)
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We provide evidence that gallium purity is the primary impediment to attainment of ultra-high mobility in a two-dimensional electron gas (2DEG) in AlGaAs/GaAs heterostructures grown by molecular beam epitaxy (MBE). The purity of gallium can be enhanced dramatically by in-situ high temperature outgassing within an operating MBE. Based on analysis of data from an initial growth campaign in a new MBE system and modifications employed for a 2 nd growth campaign, we have produced 2DEGs with low temperature mobility µ in excess of 35x10 6 cm 2 /Vs at density n=3.0x10 11 /cm 2 and µ=18x10 6 cm 2 /Vs at n=1.1x10 11 /cm 2. Our 2 nd campaign data indicate that gallium purity remains the factor currently limiting µ<40x10 6 cm 2 /Vs. We describe strategies to overcome this limitation.
Journal of the Korean Physical Society, 2020
We studied the properties of electron transport in mesoscopic GaAs/AlGaAs heterostructure without any intentional dopants in which an external electric field defined the two-dimensional electron gas (2DEG). An electrically formed 2DEG without intentional doping offers many advantages because of the absence of high concentrations of charged scattering centers. We demonstrate that the electron concentration can be easily tuned by varying the gate voltage. This tunability was observed for a high-quality 2DEG with a carrier density ranging from 0.75 to 3.34 × 10 11 cm −2 , for which the corresponding mobility ranged from 0.26 to 2.93 × 10 6 cm 2 V −1 s −1. The mobility of the 2DEG is closely followed the experimental power law for high-mobility wafers, μ ∝ n 0.7 2D .
Electron mobility limits in a two-dimensional electron gas: GaAs-GaAlAs heterostructures
Physical Review B
A theoretical model was formulated for electron scattering in a two-dimensional electron gas confined in a triangular potential well. For the first time, the effects of intersubband scattering were included. An inherent mobility limit is imposed by phonon, alloy, and remote impurity scattering. Intersubband scattering was found to play a significant role in determining this mobility limit. The model accounted very satisfactorily for the reported electron mobility characteristics in GaAs-GaA1As heterostructures. The two-dimensional electron gas confined at a GaA1As-GaAs interface has received a great deal of attention' 6 because its unique transport characteristics play a key role in a new generation of ultra-high-speed semiconductor devices. Thus, in "selectively doped" GaAlAs-GaAs heterostructures, electrons confined at the GaAs side of the interface and separated from their parent donors, which are in GaAlAs, have exhibited mobilities as high as 2& 10 cm'/Vs;~this value is about one order of magnitude greater
Very low density two-dimensional hole gas in an inverted GaAs/AlAs interface
1997
Abstract We utilize an inverted heterostructure grown on (311) A GaAs to realize a two-dimensional hole gas (2DHG) with a built-in back gate. The density of the 2DHG is easily and reproducibly varied between 5× 10 9 and 5× 10 11 cm-2. The mobility of the 2DHG is highly anisotropic in the (311) A plane.© 1997 American Institute of Physics.
Superior molecular beam epitaxy (MBE) growth on (< i> N 11) A GaAs
1999
The (311) A and (511) A planes of GaAs were used for the growth of high-quality two-dimensional hole gas (2DHG) and electron gas (2DEG) structures, respectively. A back-gated, inverted interface, AlGaAs/GaAs structure in which a 2DHG or a 2DEG was embedded was studied. This particular structure enabled the two-dimensional carrier concentration to be varied over two orders of magnitude in a single device, as well as the measurement of extremely low carrier densities in the mid 109cm− 2 range.
Role of nitrogen in the mobility drop of electrons in modulation-doped GaAsN/AlGaAs heterostructures
Solid State Communications, 2003
We report transport properties of a 2 dimension electron gas (2DEG) in molecular beam epitaxy-grown GaAs 12x N x /AlGaAs modulation-doped heterostructures. Quantum oscillations in far infrared cyclotron resonance prove the efficient electron transfer and formation of the 2DEG. The 2DEG mobility strongly depends on the N concentration in the channel layer. It shows a drastic decrease as compared to N-free samples, even for the smallest amount of N (0.02%). For this N composition, the electron effective mass was found to be 0:073m 0 : Reduced growth temperature (450 8C) was found to improve the mobility of N-containing channels. Examination of transport properties from 4 to 300 K and cyclotron resonance experiments give evidence of the presence of ionised impurity-like scattering centres in GaAsN.