Chuanjie Zhang

Anomalous hall effect in arsenic-doped HgCdTe grown by Te-rich LPE

The Hall Effect and resistivity of arsenic-doped HgCdTe epilayers grown by Te-rich liquid phase epitaxy (Te-rich LPE) have been measured in the temperature range between 20 and 300 K at a magnetic field of 2 kG. Some arsenic-doped HgCdTe layers show anomalous n-type characteristic after activation annealing. A simplified two-layer model is applied to describe the anomalous Hall Effect of the arsenic-doped HgCdTe layers. The results show that the anomalous characteristic of the epilayers is due to the n-type layer in the surface, which may be caused by the surface oxidation. Based on the model, a computer program is applied to fit the experimental curves of Hall parameters. The results show that the Hall parameters primarily depend on the charge density of the n-type surface layer. The theoretical curves based on the model are consistent well with the experimental data.

Dislocation cell structures in CdZnTe substrates and its behavior of threading into HgCdTe LPE epilayers

Dislocation cell structures in CdZnTe substrates and its behavior of threading into HgCdTe LPE epilayers were studied. A kind of dislocation cell structure of which dislocations linearly pile up to three <1 1 0> orientations on the (1 1 1) B face of CdZnTe crystal was found. The formation of this cell structure can be demonstrated by the enrichment of the dislocations through slip during the growth or cooling process. By comparing the dislocation densities and distributions of HgCdTe LPE epilayers with it of CdZnTe substrates at the constant region using an optical microscopy system, the behavior of cell structures of CdZnTe substrates threading into HgCdTe LPE epilayers were also discussed. The results show that the stored dislocation densities at the dislocation walls can significantly affect the behavior of dislocation cell structures threading into HgCdTe LPE epilayers. Dislocation cell structures of which dislocation walls have higher stored dislocation densities can appear in constant region of HgCdTe epilayers. But the dislocations of HgCdTe epilayers growth on CdZnTe substrate with lower stored dislocation densities at the dislocation walls are almost uniformly distributed.