Microdefects and electrical uniformity of InP annealed in phosphorus and iron phosphide ambiances

Microdefects originating from impurity-dislocation interactions in undoped InP that had been annealed in phosphorus and iron phosphide ambiances have been studied using optical microscopy. The electrical uniformity of the annealed wafer is improved by removing impurity aggregation around dislocations and by eliminating impurity striations in the annealing process. Compared to as-grown Fe-doped semi-insulating (SI) material, SI wafers obtained by annealing undoped InP in iron phosphide ambiances have better uniformity. This is attributed to the avoidance of Fe aggregation around dislocations and dislocation clusters, Fe precipitation and impurity striations, and is related to the use of a low concentration of Fe in the annealed material. The influence of Fe diffusion on the migration of dislocations in the annealing process has been studied and reviewed. (C) 2003 Elsevier B.V. All rights reserved.

Measurement of trace phosphorus in dichlorosilane by high-temperature hydrogen reduction gas chromatography

Dichlorosilane, a gas at normal temperature with a boiling point of 8.3 degrees C, is very difficult to sample and detect using conventional methods. We reduced phosphorus in dichlorosilane to PH3 by hydrogen at high temperature, then PH3 was separated from chlorosilanes by NaOH solution and from other hydrides by chromatographic absorption. Thus the problem of interference of chlorosilanes and other hydrides was overcome and PH, was measured by a double flame photometric detector at 526 nm. This method was sensitive, reliable and convenient and the sensitivity reached as low as 0.04 mu g/l.

Characterization of Phosphorus Diffused ZnO Bulk Single Crystals

Phosphorus was diffused into CVT grown undoped ZnO bulk single crystals at 550 and 800℃ in a closed quartz tube. The P-diffused ZnO single crystals were characterized by the Hall effect, X-ray photoelectron spectroscopy （XPS）, photoluminescence spectroscopy （PL）, and Raman scattering. The P-diffused ZnO single crystals are n-type and have higher free electron concentration than undoped ZnO, especially for the sample diffused at 800℃. The PL measurement reveals defect related visible broad emissions in the range of 420-550nm in the P-diffused ZnO samples. The XPS result suggests that most of the P atoms substitute in the Zn site after they diffuse into the ZnO single crystal at 550℃ ,while the P atom seems to occupy the O site in the ZnO samples diffused at 800℃. A high concentration of shallow donor defect forms in the P-diffused ZnO,resulting in an apparent increase of free electron concentration.