Growth temperature dependent evolutions of microstructural, optical and magnetic properties of Zn0.75Co0.25O films

Zn0.75Co0.25O films are fabricated via reactive electron beam evaporation. The influence of growth temperature on the microstructural, optical and magnetic properties of Zn0.75Co0.25O films is investigated by using x-ray diffraction, selected area electron diffraction, field emission scanning electron microscope, high resolution transmitting electron microscope, photoluminescence （PL）, field dependent and temperature dependent DC magnetization, and x-ray photoelectron spectroscopy （XPS）. It is shown that Zn0.75Co0.25O films grown at low temperatures （250-350℃） are of single-phase wurtzite structure. Films synthesized at 300 or 350℃ reveal room temperature （RT） ferromagnetism （FM）, while su for 250℃ fabricated films is found above 56 K. PL and XPS investigations show favour towards the perspective that the O-vacancy induced spin-split impurity band mechanism is responsible for the formation of RT FM of Zn0.75Co0.25O film, while the superparamagnetism of 250℃ fabricated film is attributed to the small size effect of nanoparticles in Zn0.75Co0.25O film.     

Ag/ZnO纳米结构的荧光增强效应

利用化学合成方法制备了Ag纳米线和ZnO量子点。对这两种纳米结构的表面形貌、晶体结构和光学性质分别进行了研究。结果表明：Ag纳米线和ZnO量子点均为单晶结构,平均直径分别为160 nm和5 nm左右。将Ag纳米线混入ZnO量子点可以使其紫外荧光显著增强,其中位于345 nm和383 nm 的荧光分别增强30倍和12倍。这与Ag纳米线和ZnO量子点混合体系的局域表面等离子体共振耦合吸收峰位相一致,说明该体系存在两种共振耦合模式。该研究结果为将来开发ZnO基纳米发光器件提供了一条新的途径。     

侧向腐蚀在1.3μm垂直腔面发射激光器中的应用

研究了广泛应用于垂直腔面发射激光器(VCSEL)等I-V族光电子器件制作的侧向腐蚀技术.分别采用C6H8O7:H2O2溶液、HCl:H3PO4溶液对InAlAs材料,InP材料进行了侧向腐蚀试验,获得了较稳定的速率,并对其腐蚀机制和晶向选择性进行了分析.采用侧向腐蚀技术制备了电流限制孔径分别为11μm和5 μm的1.3...     

Ultraviolet and Deep-Ultraviolet Emissions from c-MgxZn1-xO/MgO Ultrathin Multilayer Heterostructures

Cubic phase MgxZn1-x O/MgO multilayer heterostructures （c-Mgx Zn1-xO/MgO MHs） are grown on Si（100） and quartz substrates by reactive electron beam evaporation at low temperature （250℃）. Cross-sectional morphology observations by field-emission scanning electron microscopy show the legible interfaces of c-MgxZn1-x O/MgO MHs. X-ray diffraction demonstrates that c-MgxZn1-xO/MgO MHs are of highly （100）-oriented. Optical trans- mission investigations of c-Mgx Zn1-x O/MgO MHs on quartz substrates reveal the coexistence of the two phases, c-MgxZn1-xO and MgO. Photoluminescence examination indicates the emergence of deep-ultraviolet emission centred at about 290nm along with the blue shift of the ultraviolet emission from 405nm to 39Gnm when the nominal thickness of c-MgxZn1-xO well layers of MHs is diminished to 3nm, which is probably originated from quantum confinement effect.     

掩埋隧道结在长波长VCSEL结构中的应用

采用气态源分子束外延技术在InP(100）衬底上分别生长了δ掺杂的p+-AlIn-As-n+-InP和p+-InP-n+-InP两种隧道结结构，用电化学C-V和I-V特性曲线表征了载流子浓度和电学特性，发现p+-AlInAs-n+-InP隧道结性能优于p+-InP-n+-InP隧道结. 在InP(100）衬底上生长了包含p+-AlInAs-n+-InP掩埋隧道结和多量子阱有源层的1.3μm垂直腔面发射激光器（VCSEL）结构，测试得出其开启电压比普通的pin结VCSEL小，室温下其电致发光谱波长为1.29μm.     

利用同步辐射光电子能谱技术研究Pb1-xSrxTe薄膜的能带移动及其组成异质结能带带阶

利用同步辐射光电子能谱技术研究了低Sr组分时Pb_(1-x)Sr_xTe薄膜能带的移动规律,并计算了Pb_(1-x)Sr_xTe/Pb Te异质结中导带帯阶所占比率.当不考虑应力时,该异质结界面导带带阶比率Qc=ΔEC/ΔEg=0.71.当考虑应力时,PbTe能带发生L能谷与O能谷的劈裂,其导带带阶比率分别为QLC=0.47和QOC=0.72.Pb_(1-x)Sr_xTe/Pb Te异质结界面具有类型Ⅰ的能带排列结构,这说明Pb_(1-x)Sr_xTe/PbTe型量子阱或量子点对电子与空穴都有较强的限制能力.该异质结能带帯阶的精确测量有利于该类三元系半导体异质结在中红外光电器件的研发和应用中发挥重要作用.     

长波长VCSEL结构中的欧姆接触工艺

简要叙述了欧姆接触工艺在长波长垂直腔面发射激光器(VCSEL)制作中的重要作用.采用圆环传输线方法(CTLM)研究了应用于长波长VCSEL结构的p型InGaAsP和InP材料与Ti-Au的接触特性,发现p-InGaAsP与Ti-Au经高温退火后能获得欧姆接触,其最低比接触电阻值可达6.49×10-5Ω·cm2.将此工艺结果应用于1.3 μm VCSEL结构中,发现其开启电压和串联电阻显著减小.     

Effects of annealing process on characteristics of fully transparent zinc tin oxide thin-film transistor

Annealing effect on the performance of fully transparent thin-film transistor （TTFT）, in which zinc tin oxide （ZnSnO） is used as the channel material and SiO2 as the gate insulator, is investigated. The ZnSnO active layer is deposited by radio frequency magnetron sputtering while a SiO2 gate insulator is formed by plasma-enhanced chemical vapor deposition. The saturation field-effect mobility and on/off ratio of the TTFT are improved by low temperature annealing in vacuum. Maximum saturation field-effect mobility and on/off ratio of 56.2 cm2/（V.s） and 3×10^5 are obtained, respectively. The transfer characteristics of the ZnSnO TPT are simulated using an analytical model and good agreement between measured and the calculated transfer characteristics is demonstrated.     

MBE生长PbSe/PbSrSe量子阱结构的光致中红外发光的研究

研究了分子束外延技术生长的PbSe/PbSrSe多量子阱结构的中红外光致荧光现象.高分辨率X射线衍射（HRXRD）谱观察到了多量子阱所特有的多级卫星峰,表明量子阱界面陡峭.变温光致荧光谱测量显示量子阱结构对电子空穴有强的限制效应,在相同温度下,量子阱样品的荧光峰峰位相对PbSe体材料有一定的蓝移.发现量子阱样品的荧光强度同温度有关,温度从150 K上升到230 K时,荧光强度逐渐增大,温度继续升高,荧光强度缓慢下降,但在高于室温时,仍能观察到较强的荧光发射,这说明该量子阱结构材料具有应用于室温工作的中红外 关键词： PbSe/PbSrSe多层量子阱（MQWs） 光致中红外荧光 高分辨X射线衍射（HRXRD）     

PbTe/CdTe量子点的光学增益

PbTe/CdTe量子点是一类新型异系低维结构材料,实验发现具有强的室温中红外光致发光现象.为研究这一材料体系的发光特性,建立了理论模型,计算了PbTe/CdTe量子点的光学跃迁和增益.模型基于k·p包络波函数方法并考虑了PbTe能带结构的各向异性.分析了量子点光学增益与量子点尺寸、注入载流子浓度的关系.结果表明,当注入载流子浓度在(0.3—3)×10¹⁸cm^-3范围时,尺寸为15—20nm的量子点可以产生 关键词： PbTe/CdTe量子点 光学增益 铅盐矿半导体