Volume 87, Issue 2, 15 January 2000
Index of content:
Formation of a two-dimensional electron gas in an inverted undoped heterostructure with a shallow channel depth87(2000); http://dx.doi.org/10.1063/1.371965View Description Hide Description
We investigated the dependence of transport characteristics of a two-dimensional electron gas(2DEG) on channel depth in an inverted undoped GaAs/AlGaAs heterostructure. We succeeded in forming a high-mobility 2DEG in a sample with 70 nm channel depth. We controlled the carrier density by varying the back-gate bias over a wide range. The highest mobility reached at The relation between mobility and carrier density is determined: the mobility decreases in a low-carrier-density region as the channel depth decreases. This result suggests that the scattering due to the remote surface charges plays a more significant role.
Ion channeling studies on mixed phases formed in metalorganic chemical vapor deposition grown Mg-doped GaN on87(2000); http://dx.doi.org/10.1063/1.371966View Description Hide Description
Rutherford backscattering spectrometry and ion channeling were used to determine the relative quantities of wurtzite and zinc-blende phases in metalorganic chemical vapor deposition grown Mg-doped GaN(0001) on an substrate with a GaN buffer layer. Offnormal axial channeling scans were used. High-resolution x-ray diffraction measurements also confirmed the presence of mixed phases. The in-plane orientation was found to be The effects of rapid thermal annealing on the relative phase content, thickness and crystalline quality of the GaN epilayer were also studied.
Comment on “Assignment of the Raman active vibration modes of using micro-Raman scattering” [J. Appl. Phys. 85, 7380 (1999)]87(2000); http://dx.doi.org/10.1063/1.371969View Description Hide Description
In this comment to a recent experimental paper by Honda et al. [J. Appl. Phys. 85, 7380 (1999)], we report first-principles calculations of phonon modes of which theoretically confirm the experimental micro-Raman assignments. In addition, the theory is able to locate the “missing” mode, and we show that this mode is a bond-stretching mode. Hence, it is not in the low-frequency band as previously believed, but rather at intermediate frequency. We discuss the possible reasons this mode is “missing” in the spectra, and show that the application of high pressure will separate this mode from others.