Hole mobility enhancement in GaAs/p-Al0.3Ga0.7As QW-HEMT structures with (4 1 1)A super-flat interfaces grown by MBE

Satoshi Hiyamizu, Keisuke Shinohara, Kenji Kasahara, Yasuyuki Shimizu, Satoshi Shimomura, Richard A. Kiehl

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Be-doped GaAs/p-Al0.3Ga0.7As QW-HEMT structures with well width of Lw = 2, 7, 10, 20 and 50 nm were simultaneously grown on (4 1 1)A and (1 0 0) GaAs substrates by MBE. Be-doping concentration in the p-Al0.3Ga0.7As layer was 1.4 × 1018cm-3, and the undoped Al0.3Ga0.7As spacer layer was 6 nm thick. Hole concentration was about 6 × 1011 cm-2 for Lw > 7 nm. Hole mobility at 10K in the conventional (1 0 0) samples remained almost constant (about 20 000 cm2/(Vs) for the current in the [0 1 1] direction) with decreasing Lw down to 7 nm and it rapidly decreased to 2760 cm2/(Vs) at Lw = 2 nm. On the other hand, in the (4 1 1)A samples, hole mobility (10 K) increased from 17 500 cm2/(Vs) (Lw = 50 nm) to 33 900 cm2/(V s) (Lw = 10 nm) and dropped rapidly down to 4090 cm2/(V s) (Lw = 2 nm) for a current direction of [0 1 1]. This significant enhancement of hole mobility in the (4 1 1)A samples is mainly due to (1) the significantly reduced interface roughness scattering of 2DHG when using the (4 1 1)A super-flat interfaces and (2) the reduced effective mass of holes in the narrow (4 1 1)A QWs (Lw = 7-20 nm). Shubnikov-de Haas (SdH) measurements on the (4 1 1)A QW sample (Lw = 7 nm) confirmed the reduced effective mass (0.30m0) of holes.

Original languageEnglish (US)
Pages (from-to)232-236
Number of pages5
JournalPhysica E: Low-Dimensional Systems and Nanostructures
Volume2
Issue number1-4
DOIs
StatePublished - Jul 15 1998
Externally publishedYes

Keywords

  • (4 1 1)A
  • 2DHG
  • GaAs/AlGaAs HEMT
  • Hall mobility

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics

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