Detection of lead ions with AlGaAs/InGaAs pseudomorphic high electron mobility transistor

Lead poisoning is a serious environmental concern, which is a health threat. Existing technologies always have some drawbacks, which restrict their application ranges, such as real time monitoring. To solve this problem, glutathione was functionalized on the Au-coated gate area of the pseudomorphic high electron mobility transistor (pHEMT) to detect trace amounts of Pb²⁺. The positive charge of lead ions will cause a positive potential on the Au gate of the pHEMT sensor, which will increase the current between the source and the drain. The response range for Pb²⁺ detection has been determined in the concentrations from 0.1 pmol/L to 10 pmol/L. To our knowledge, this is currently the best result for detecting lead ions.     

快速退火对ZnTe外延层性能及In电极的影响

研究了在GaAs(001)衬底上外延生长的本征ZnTe薄膜样品在氮气氛中450～550℃下的快速退火行为。对于1 min退火的样品,随着退火温度的升高,ZnTe(004)峰双晶X射线(DCXRD)摇摆曲线的半高宽(FWHM)逐渐下降;样品表面粗糙度均方根值(RMS)由退火前的5.3 nm下降至4.7 nm左右。对于450℃退火5 min的样品,其晶体质量与550℃退火1 min的样品相当,但RMS值下降到4.26 nm。ZnTe薄膜表面的In电极之间在未退火时呈高阻状态,在适当条件下退火后In电极之间可以导通,且随着退火温度的降低,所需的退火时间将延长。但550℃退火时In电极的外观形貌发生改变且不能导通。     

ZnCl2掺杂n型ZnSe的分子束外延生长

利用分子束外延(MBE)技术,以5N的ZnCl2作为掺杂源,在半绝缘GaAs (001)衬底上异质外延生长ZnSe:Cl单晶薄膜.研究发现,掺入ZnCl2后,ZnSe外延层的结晶质量和表面形貌与本征ZnSe外延层相比变差,双晶X射线摇摆曲线(DCXRC)的ZnSe (004)衍射峰半峰宽(FWHM)从432 arcsec增大到529 arcsec,表面均方根粗糙度(RMS)从3.00 nm增大到3.70nm.当ZnCl2掺杂源炉的温度为170℃时,ZnSe样品的载流子浓度达到1.238×1019 cm-3,可以满足结型器件制作和隧道结材料设计的要求.