K元素对CdS晶体光学及电学性能的影响

采用物理气相输运(PVT)法生长了直径为50 mm的K掺杂CdS晶体,对掺杂和未掺杂的CdS晶片进行显微观察、二次离子质谱(SIMS)成分分析、红外光谱透过率以及霍尔效应测试,研究了K元素掺杂对CdS晶体光学及电学性能的影响.生长时用KCl进行掺杂.显微观察显示,掺杂KCl后CdS晶体的微观形貌没有明显变化;SIMS成分测试表明,晶体中引入的杂质主要是K元素,而Cl元素未掺入晶体中.红外光谱透过率发现掺杂K元素的CdS晶体相比于未掺杂晶体,不仅在波长为2.5～ 10 μm内红外透过率显著下降,而且在波长为10μm以上时红外透过率甚至低于15％.另外,K元素掺杂CdS晶体电学性能也发生变化,晶体迁移率也由未掺杂的318 cm2/ (V·s)下降为146 cm2/ (V·s).     

Effects of current density on the corrosion behaviour of anodized aluminum alloy in FeCl3 solution

In the present study,2024 aluminum alloy specimen was anodized in acetic acid and oxalic acid electrolytcs.Effects of the currcnt dcnsity on thc microstructure and corrosion resistance of anodic oxide ...     

Study on the characterization and technology of Cu thin-film temperature sensor fabricated on aluminum alloy

In the present study,anodic films on aluminium alloy was used as the dielectric layer for Cu thinfilm temperature sensor,and then Cu film was deposited by unbalanced magnetron sputtering ion plating as the sensitive layer.Microstructure and surface morphologies of Cu film were investigated by optical microscope（OM）,atomic force microscope（AFM） and scanning electron microscope（SEM）.Electrical properties of Cu thin-film temperature sensor were tested by four-point probe technique and Digit Multimeter.The results showed that the surface roughness of anodic films can be reduced from Ra 58.096 nm to Ra 16.335 nm by proper polishing.Continual Cu stripes can be obtained both on polished anodic alumina film and smooth alumina wafer by etching after Cu film annealing.The resistivity of Cu films before and after 300 ℃ as well as 400 ℃ annealing are 12.48 mΩ·cm,5.48 mΩ·cm and 4.83 mΩ·cm,respectively.The resistances of Cu thin-film temperature sensor in 70 ℃ and 0 ℃ are 946.5 Ω and 761.15 Ω respectively.The temperature coefficient of resistivity（TCR） of the sensor is 3479 × 10^{- 6} /℃.     

导模法生长大尺寸高质量β-Ga2O3单晶

以高纯Ga2O3为原料,使用自主设计的单晶生长炉,采用导模(EFG)法生长了2英寸(1英寸=2.54 cm)未掺杂的高质量β-Ga2O3单晶.研究了保护气氛对抑制Ga2O3原料高温分解速率的影响,对制备的β-Ga2O3单晶的晶体质量、位错和光学性能进行了测试和表征.结果表明,CO2保护气氛能够极大地抑制Ga2O3材料的高温分解,当CO2生长气压为1.5×105 Pa时,Ga2O3的平均分解速率低于1 g/h.(100)面β-Ga2O3单晶的X射线衍射(XRD)摇摆曲线测试结果表明,其半高宽低至29 arcsec,表明晶体具有较高的质量;对晶体(100)面进行了位错腐蚀,结果显示其位错密度较低,约为4.9×104 cm-2;傅里叶变换红外光谱仪测试结果显示,β-Ga2O3单晶在紫外、可见光透过率达到80％以上.     

大尺寸β-Ga2O3晶片的机械剥离及性能北大核心

针对β—Ga2O3单晶易解理的特性,研究了晶体形状对其（100）主解理面的机械剥离影响。结果表明,棱角较为平缓的体单晶机械剥离时容易出现碎裂,而棱角尖锐的体单晶极易实现机械剥离,并且成功剥离出尺寸大于30mm×10mm的β-Ga2O3单晶片。测试了剥离的β-Ga2O3单晶片微观形貌、表面粗糙度、晶体质量以及位错。结果显示,剥离的β-Ga2O3单晶片具有高的表面质量;原子力显微镜（AFM）测试表明,晶片整体表面粗糙度小于1nm,存在0．5～1nm厚的原子台阶;晶片X射线衍射（XRD）摇摆曲线测试显示,其半高宽（FWHM）值低至50arc-sec,表明晶体具有较高的质量;对晶片进行位错腐蚀,结果显示制备的β-Ga2O3晶片具有较低的位错密度,约为6×10^4cm^-2。     

镉气氛退火对CdS单晶材料性能的影响

硫化镉(CdS)是一种光电性能优异的Ⅱ-Ⅵ族直接跃迁、宽带隙化合物半导体材料。将本征高阻的CdS单晶材料在镉气氛中高温退火,并对退火后的CdS材料进行电学、光学特性表征。测试结果表明,镉气氛退火可使本征高阻的CdS单晶转变为低阻CdS材料,从而实现对CdS材料电学特性调控。