Influence of light on the confinement potential of GaAs/AlxGa1

J.G. Michels

¹

,

R.J. Nicholas

²

,

G.M. Summers

³

et al.

Magnetoabsorption in InSb quantum-well heterostructures

“…6 This behavior is known as resonant subband Landau level coupling ͑RSLC͒ and is a convenient way of determining the subband energy spacing in a 2DEG. 8 The InSb/ Al x In 1−x Sb heterostructures reported here were grown by solid source molecular beam epitaxy ͑MBE͒ on semi-insulating GaAs substrates. In growth order, the material consists of a strain accommodation system followed by a 3 m Al 0.10 In 0.90 Sb strain-relaxed lower barrier layer, a 30 nm InSb quantum well, and a 50 nm upper barrier layer of Al 0.…”

High-lying thermally excited subbands of two-dimensional electron gases in GaAs/AlGaAs heterojunction for modulation-doped field-effect transistor

“…The basic properties of this 2DEG system, especially the energy subband structures due to triangular-like confinement potential in the perpendicular direction of the interface, have been investigated extensively for years. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Several spectroscopic techniques, such as light scattering, 4,5 absorption spectroscopy 6,7 intersubband-cyclotron combined resonance, 8 and the so-called resonant subband-Landau-level coupling ͑RSLC͒ method 9-16 which will be adopted in this investigation, have been used to determine the subband structures of 2DEG system. Up to now, most of the existing experimental results are for the low-lying subbands.…”

“…Up to now, most of the existing experimental results are for the low-lying subbands. [4][5][6][7][8][9][10][11][12][13][14][15][16] However, in general, the MODFET devices operate at 77 K or room temperature. Under these circumstances, the electrons will partially distribute at the high-lying subbands due to the thermal excitation.…”

Current flow past an etched barrier: field emission from a two-dimensional electron gas

“…In the present devices, this situation is brought about by making V g sufficiently positive. It is known, however, that illumination with an LED at low temperatures also flattens the bands in the GaAs by neutralizing acceptors deep in the substrate [2]. Indeed, we have previously seen very similar behaviour in etched barriers on standard heterostructures with no back gate, but only after illumination with red light at 4.2 K [4], and we have subsequently found that a voltage applied to the chip carrier has much the same effect on the characteristics as has V g in the present devices.…”

“…However, in order for there to be complete confinement there must also exist an electric field in the GaAs substrate pushing the electrons towards the heterojunction. In practice, this substrate field is typically provided by negative charge on residual acceptors in the substrate and surface boundary conditions [2]. A very interesting situation arises if this confinement field vanishes.…”