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

我们将购置一台带有光电接口的氦气静压装置和一台Kulicke和Soffa引线键合机来研究III族氮化物的压电常数。焊接机需要将金属线连接到半导体上，以便于导电。这种仪器将很好地补充我们现有的努力，由NSF资助，专门处理氮化物中的极化问题。这项工作将得到我们强大的MBE和MOCVD内部氮化物生长工作的支持。我们将与明尼苏达大学的内森教授合作，他已经在氮化物中进行了这类实验。已经进行了非门控霍尔栅电阻率与应力关系的初步实验。电阻率随时间缓慢漂移（时间常数为100至1000秒）。先前在GaAs中观察到的类似效应被归因于与浅施主相关的缺陷中心，称为DX中心。然而，InGaN的效应更为复杂，但它让人联想到早期在GaAs中观察到的持续光电导类型。显然，捕获效应必须与压电效应分开。 这一研究对氮化物电子器件的实际应用具有重要意义.氦气静水压装置，配有电气和光学接口，将从波兰Unipress购买。（121 749美元）焊线机，将从Kulicke Soffa购买（型号4524 -20092.50美元）Hadis Morkoc弗吉尼亚联邦大学电气工程与物理系601 W。Main Street P. O.信箱843072 里士满，弗吉尼亚州23284-3072

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