简介：最近，ATI在其最新的Radeon9600XT和9800XT显卡上应用了一项叫“Overdrive“的新技术，但是很多选购了此类显卡的朋友却发现在驱动程序找不到相关的设置，以至无法实现“Overdrive“功能。在确认问题不是出自驱动程序版本以后，用户开始愤怒了。那么“Overdrive”究竟是什么？没有“Overdrive”会对显卡性能产生什么样的影响？而普通用户又应该如何看待这个问题呢？

简介：Thedegradationmechanismofenhancement-modeAlGaN/GaNhighelectronmobilitytransistors(HEMTs)fabricatedbyfluorineplasmaionimplantationtechnologyisonemajorconcernofHEMT’sreliability.Itisobservedthatthethresholdvoltageshowsasignificantnegativeshiftduringthetypicallong-termon-stategateoverdrivestress.Thedegradationdoesnotoriginatefromthepresenceofas-growntrapsintheAlGaNbarrierlayerorthegeneratedtrapsduringfluorineionimplantationprocess.Bycomparingtherelationshipsbetweentheshiftofthresholdvoltageandthecumulativeinjectedelectronsunderdifferentstressconditions,agoodagreementisobserved.Itprovidesdirectexperimentalevidencetosupporttheimpactionizationphysicalmodel,inwhichthedegradationofE-modeHEMTsundergateoverdrivestresscanbeexplainedbytheionizationoffluorineionsintheAlGaNbarrierlayerbyelectronsinjectedfrom2DEGchannel.Furthermore,ourresultsshowthattherearefewnewtrapsgeneratedintheAlGaNbarrierlayerduringthegateoverdrivestress,andtheionizedfluorineionscannotrecapturetheelectrons.