Acquistion of Instrumentation for Stress Effects on the Electrical Properties of Group III-Nitride Modulation Doped Heterostructures

点击翻译按钮获取中文摘要

A Helium gas hydrostatic pressure apparatus with electrical and opticalaccess and a Kulicke and Soffa wire bonder will be acquired to investigatepiezoelectric constants in III-nitrides. The bonder is needed to attachmetallic wires for electrical access to the semiconductor for conductancemeasurements. This instrumentation will nicely complement our existingeffort funded by NSF, which deals specifically with the polarization issuesin nitrides. The effort will be supported by our strong in house nitridegrowth effort with MBE and MOCVD. Prof. Nathan of the University ofMinnesota, with whom we will collaborate, has already conducted these sortsof experiments in nitrides. Initial experiments of resistivity vs. stresson un-gated Hall bars have already been conducted. The resistivity exhibitsslow long term drifts (time constants of order 100 to 1000 seconds. Similareffects observed earlier in GaAs have been ascribed to a defect centerassociated with shallow donors called the DX center. However, the effect inGaN is more complex, but it is reminiscent of the type of persistentphotoconductivity observed in GaAs in the early stages of development.Clearly trapping effects will have to be separated from the piezoelectriceffects. Such a study is crucial to the practical application electronicnitride devices.The requested instrument consists of 1. Helium gas hydrostatic pressure apparatus with electrical and opticalaccess, which will be purchased from Unipress, Poland. ($121,749) Wire bonder which will be purchased from Kulicke & Soffa (model 4524 -$20,092.50) Hadis MorkocVirginia Commonwealth UniversityDepartment of Electrical Engineering and Physics Department601 W. Main Street P. O. Box 843072 Richmond, VA 23284-3072