Abstract
By using the picosecond ultrasonics technique, piezoelectric effect in GaAs undoped sample at both faces (A(111) and B(-1-1-1)) is experimentally studied. We demonstrate that piezoelectric generation of sound can dominate in GaAs material over the deformation potential mechanism even in the absence of static externally applied or built-in electric field in the semiconductor material. In that case, the Dember field, caused by the separation of photo-generated electrons and holes in the process of supersonic diffusion, is sufficient for the dominance of the piezoelectric mechanism during the optoacoustic excitation. The experimental results on the sample at both faces reveal that in one case (A face), the two mechanisms, piezoelectric effect and deformation potential, can compensate each other leading to a large decrease of the measured Brillouin oscillation magnitude.
Highlights
Picosecond ultrasonics [1] is a technique which permits to carry on contactless and non-destructive investigation of the elasticity of different kinds of materials and structures at nanoscales [2,3,4]
We present here new experimental results and analysis of the generation efficiency of inverse piezoelectric effect driven by Dember field versus deformation potential in non-doped GaAs
The Brillouin signal analysis shows clear difference between generation processes involved for A[111] and B[-1-1] orientations. This magnitude increases with pump fluence for face B[-1-1] (Fig. 1c and 2a), while there is a given pump fluence close to 1,55 μJ/cm2 where it nearly vanishes for face A[111] (Fig. 1b and 2a)
Summary
Picosecond ultrasonics [1] is a technique which permits to carry on contactless and non-destructive investigation of the elasticity of different kinds of materials and structures at nanoscales [2,3,4]. We demonstrate that piezoelectric generation of sound can dominate in GaAs material over the deformation potential mechanism even in the absence of static externally applied or built-in electric field in the semiconductor material.
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