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Observation of strain relaxation in Si1-xGex layers by optical and electrical characterisation of a Schottky junction |
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| Authors: | R Turan B Aslan O Nur MYA Yousif M Willander |
| Institution: | Department of Physics, Middle East Technical University, 06531 Ankara, Turkey, TR Physical Electronics and Photonics, Physics Department, Microtechnology Center at Chalmers (MC2), Chalmers University of Technology and G?teborg University, 412 96 G?teborg, Sweden, SE |
| Abstract: | We have studied the effect of the strain relaxation on the band-edge alignments in a Pt/p-Si1-xGex Schottky junction with x=0.14 by internal photoemission spectroscopy and current–voltage measurements. We have shown that the variations in the band-edge alignments can be observed directly by measuring the optical and electrical properties of a simple Schottky junction. The strain in the Si1-xGex layer has been partially relaxed by thermal treatments at two different temperatures. The degree of relaxation and other structural changes have been determined by a high-resolution X-ray diffractometer. Both optical and electrical techniques have shown that the barrier height of the Pt/Si0.86Ge0.14 junction increases with the amount of relaxation in the Si1-xGex layer. This shows that the valence-band edge of the Si1-xGex layer moves away from the Fermi level of the Pt/Si1-xGex junction. The band-edge movement results from the increase in the band gap of the Si1-xGex layer after the strain relaxation. This result agrees with the theoretical predictions for the strain-induced effects on the Si1-xGex band structure. Received: 18 October 2000 / Accepted: 19 December 2000 / Published online: 23 March 2001 |
| Keywords: | PACS: 61 72 Hh 73 30 +y 85 60 Gz |
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