| Author | H. Chung, W. Si, M. Dudley, A. Anselmo, D.F. Bliss, A. M. Maniatty, H. Zhang and V. Prasad |
|---|---|
| Title | Characterization of Structural Defects in MLEK Grown InP Single Crystals Using Synchrotron White Beam X-Ray Topography |
| Year | 1997 |
| Journal | Journal of Crystal Growth |
| Volume | 174 |
| Pages | 230-237 |
| Abstract | Structural defects in MLEK grown InP single crystals have been studied using synchrotron white beam X-ray topography. Results here are represented for both a S-doped boule which was wafered longitudinally (i.e., parallel to the growth axis) and a Fe-doped boule which was wafered laterally (i.e., perpendicular to the growth axis). For longitudinal wafers from the S-doped boule, slip bands were observed to have nucleated from high-stress concentration located at the peripheral regions of the boule and to have propagated into the interior of the samples. In the same crystals, the growth interface morphology at different stages of crystal growth was determined. The interface is revealed as contours of equal lattice parameter, visible via strain contrast, as the concentration of the dopant changed periodically during growth. The interface shape was observed to be slightly convex to the melt, once the growth conditions were stabilized. For the laterally sliced wafers from the Fe-doped boule, systematic studies revealed that the density of dislocations changed during growth. A high density of uniformly distributed dislocations were observed in wafers taken from the early and later stages of growth. On the other hand, dislocations in well-defined four-fold symmetric distribution were observed in wafers sliced from the intermediate growth stages. The origins of this four-fold distribution were investigated using a thermal stress model which consisted of imposing a compressive radial stress, uniformly distributed around the boule circumference. The calculated stress distributions also showed four-fold symmetry in agreement with the observed dislocation distributions. |
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