F. Li et al., EFFECTS OF LOW-ENERGY ION EXPOSURE ON MODULATION-DOPED GAAS HETEROSTRUCTURES, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 11(6), 1993, pp. 2592-2596
in order to determine the electrical isolation mechanism of low energy
ions impinging on GaAs heterostructures, a systematic magnetotranspor
t study was performed on the two-dimensional electron gas (2DEG) of a
GaAs modulation doped heterostructure. Sample devices were bombarded w
ith 150 eV Ar+ ions while the room temperature resistances were measur
ed in situ. The effectiveness of photoresist as a masking material was
tested. Magnetotransport measurements were carried out in a dark cond
ition at 4.2 K, and the resistance, mobility, and carrier density of t
he 2DEG were monitored as functions of the ion exposure time. The isol
ation results are consistent with a screening model for the 2DEG elect
rons. In this model, the onset of electrical isolation is due to the b
reakdown of the screening because milling of the surface results in de
pletion of the 2DEG carriers. At present, no additional effects of the
low energy ions, such as material damage from ion penetration, have b
een confirmed