Structural properties of pressure-induced structural phase transition of Si-doped GaAs by angular-dispersive X-ray diffraction

Kung Liang Lin, Chih Ming Lin*, Yu Sheng Lin, Sheng Rui Jian, Yen Fa Liao, Yu Chun Chuang, Chuan Sheng Wang, Jenh-Yih Juang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Pressure-induced phase transitions in n-type silicon-doped gallium arsenide (GaAs:Si) at ambient temperature were investigated by using angular-dispersive X-ray diffraction (ADXRD) under high pressure up to around 18.6 (1) GPa, with a 4:1 (in volume ratio) methanol–ethanol mixture as the pressure-transmitting medium. In situ ADXRD measurements revealed that n-type GaAs:Si starts to transform from zinc-blende structure to an orthorhombic structure [GaAs-II phase], space group Pmm2, at 16.4 (1) GPa. In contrast to previous studies of pure GaAs under pressure, our results show no evidence of structural transition to Fmmm or Cmcm phase. The fitting of volume compression data to the third-order Birch–Murnaghan equation of state yielded that the zero-pressure isothermal bulk moduli and the first-pressure derivatives were 75 (3) GPa and 6.4 (9) for the B3 phase, respectively. After decompressing to the ambient pressure, the GaAs:Si appears to revert to the B3 phase completely. By fitting to the empirical relations, the Knoop microhardness numbers are between HPK = 6.21 and HA = 5.85, respectively, which are substantially smaller than the values of 7–7.5 for pure GaAs reported previously. A discontinuous drop in the pressure-dependent lattice parameter, N–N distances, and V/V0 was observed at a pressure of 11.5 (1) GPa, which was tentatively attributed to the pressure-induced dislocation activities in the crystal grown by vertical gradient freeze method.

Original languageEnglish
Article number117
Pages (from-to)1-6
Number of pages6
JournalApplied Physics A: Materials Science and Processing
Volume122
Issue number2
DOIs
StatePublished - 1 Feb 2016

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