Photoluminescence and X-Ray Photoelectron Spectroscopy of p-Type Phosphorus-Doped ZnO Films Prepared by MOCVD

Reproducible p-type phosphorus-doped ZnO （p-ZnO：P） films are prepared on semi-insulating InP substrates by metal-organic chemical vapour deposition technology. The electrical properties of these films show a hole concentration of 9.02 × 10^17 cm ^-3, a mobifity of 1.05 cm^2 /Vs, and a resistivity of 6.6 Ω.cm. Obvious acceptorbound-exciton-related emission and P-induced zinc vacancy （Vzn） emission are observed by low-temperature photoluminescence spectra of the films, and the acceptor binding energy is estimated to be about 125meV. The local chemical bonding environments of the phosphorus atoms in the ZnO are also identified by x-ray photoelectron spectra. Our results show direct experimental evidence that Pzn-2Vzn shallow acceptor complex most likely contributes to the p-type conductivity of ZnO：P films.     

ZnO-Based Transparent Thin-Film Transistors with MgO Gate Dielectric Grown by in-situ MOCVD

ZnO transparent thin-film transistors with MgO gate dielectric were fabricated by in-situ metal organic chemicM vapor deposition （MOCVD） technology. We used an uninterrupted growth method to simplify the fabrication steps and to avoid the unexpectable contaminating during epitaxy process. MgO layer is helpful to reduce the gate leakage current, as well as to achieve high transparency in visible light band, due to the wide band gap （7. 7eV） and high dielectric constant （9.8）. The XRD measurement indicates that the ZnO layer has high crystal quality. The field effect mobility and the on/off current ratio of the device is 2.69cm^2V^-1s^-1 and - 1 × 10^4, respectively.     

SiN插入层对GaN外延膜应力和光学质量的影响

研究了MOCVD系统中原位SiN插入层对GaN薄膜应力和光学性质的影响。采用SiN插入层后,GaN薄膜的裂纹数量大大减少,薄膜所承受的张应力得到了一定的释放。同时,GaN薄膜的缺陷密度降低一倍,晶体质量得到了极大的改善。研究表明,位错密度的降低在GaN薄膜中留存较大的残余应力,补偿了降温过程中所引入的张应力。同样,随着SiN插入层的应用,低温PL谱的半峰宽降低,薄膜光学质量提高。最后研究了PL谱发光峰与应力的关系,得到了一个-13.8的线性系数。     

MOCVD法制备的p-ZnO/n-SiC 异质结器件及其电致发光性能

采用光辅助金属有机化学汽相沉积(PA-MOCVD)法在n-SiC(6H)衬底上制备出As掺杂的p型ZnO薄膜,并制备出相应的p-ZnO:As/n-SiC异质结器件。X射线衍射(XRD)和光致发光(PL)测试表明,ZnO薄膜具有较好的结构和光学特性。电流-电压(I-V)测试结果表明,该型异质结器件具有良好的整流特性,开启电压为5.0 V,反向击穿电压约为-13 V。正向偏压下,器件的电致发光(EL)谱表现出两个分别位于紫外和可见光区域的发光峰,通过和ZnO、SiC的PL谱对照,证实异质结器件的发光峰来源于ZnO侧的辐射复合。     

Effect of Au/Ni/4H–SiC Schottky junction thermal stability on performance of alpha particle detection

Au/Ni/n-type 4H–SiC Schottky alpha particle detectors are fabricated and annealed at temperatures between 400℃ and 700℃ to investigate the effects of thermal stability of the Schottky contact on the structural and electrical properties of the detectors. At the annealing temperature of 500?C, the two nickel silicides(i.e., Ni_(31)Si_(12) and Ni_2Si) are formed at the interface and result in the formation of an inhomogeneous Schottky barrier. By increasing the annealing temperature,the Ni_(31)Si_(12) transforms into the more stable Ni_2Si. The structural evolution of the Schottky contact directly affects the electrical properties and alpha particle energy resolutions of the detectors. A better energy resolution of 2.60% is obtained for 5.48-MeV alpha particles with the detector after being annealed at 600℃. As a result, the Au/Ni/n-type 4 H–SiC Schottky detector shows a good performance after thermal treatment at temperatures up to 700℃.     

利用MOCVD技术生长As掺杂的p-ZnMgO薄膜

利用GaAs夹层掺杂的新方法,采用金属有机化学气相沉积(MOVCD)技术,通过控制生长温度,在蓝宝石衬底上成功制备出As掺杂的p型ZnMgO薄膜.利用X射线衍射分析(XRD)、霍尔效应测试和光致发光(PL)谱等表征方法对薄膜的晶体结构、电学性能和光学特性进行分析.结果表明:高温生长的ZnMgO薄膜具有良好的c轴取向性;...     

400nm高性能紫光LED的制作与表征(英文)

利用金属有机物化学气相沉积技术在蓝宝石衬底表面制备了带有p-AlGaN电子阻挡层的400 nm高性能紫光InGaN多量子阱发光二极管。制作了3种紫光LED,分别带有不同p-AlGaN电子阻挡层结构:Al摩尔分数为9%的p-AlGaN电子阻挡层;Al摩尔分数为11%的p-AlGaN电子阻挡层;Al摩尔分数为20%的10对p-AlGaN/GaN超晶格电子阻挡层。带有高浓度Al电子阻挡层的紫光LED的光输出功率高于低浓度Al电子阻挡层的紫光LED。带有10对p-AlGaN/GaN超晶格电子阻挡层的紫光LED的光输出功率获得了极大的提高,在20 mA注入电流时测试得到的光输出功率为21 mW。此外,该LED同时显示了在高注入电流下接近线性的I-L特性曲线和在LED芯片表面均匀的发光强度分布。     

衬底弯曲度对GaN基LED芯片性能的影响

利用低压MOCVD系统在弯曲度值不同的蓝宝石衬底上生长了GaN基LED外延结构并制作芯片。测量了芯片的主要电学和光学参数,并分析了衬底弯曲度值对芯片性能的影响。分析结果表明:存在弯曲度的衬底预先弛豫了外延层中的部分应力,改善了外延层的质量,从而提高了LED芯片的性能。随着衬底弯曲度值的逐渐增加,下层GaN对有源层中InGaN材料的压应力作用不断减小,导致芯片的主波长逐渐发生蓝移。     

AlGaN/GaN高电子迁移率晶体管温度传感器特性

本文制作了基于无栅AlGaN/GaN高电子迁移率晶体管结构的温度传感器,并对其温度相关的电学特性进行了表征.实验测试了器件从50℃到400℃的变温电流-电压特性,研究了器件灵敏度随着器件沟道长宽比的变化,并研究了在300—500℃高温的空气和氮气中经过1 h恒温加热后器件的电学特性变化.理论与实验研究结果表明,随着器件沟道长宽比的增大,器件的灵敏度会随之上升;在固定电流0.01 A下,器件电压随温度变化的平均灵敏度为44.5 mV/℃.同时,稳定性实验显示器件具有较好的高温保持稳定性.     

光辅助对MOCVD法制备ZnO薄膜性能的影响

采用光辅助金属有机化学气相沉积(MOCVD)技术在(0001)蓝宝石衬底上制备了ZnO薄膜。通过X射线衍射、透射光谱和霍尔测试等研究了光照对MOCVD法制备的ZnO薄膜的影响。实验结果表明,引入光辅助后制备的ZnO薄膜,其结晶质量和光学质量均得到改善。分析认为,这主要是由于光辅助有助于提高锌有机源的分解效率,并且高能量的光子可为反应吸附的原子提供足够高的激活能,从而易于其迁移到合适的晶格位置所致。同时我们还发现,有光照和无光照条件下制备的ZnO薄膜均呈n型导电,但有光照条件下制备的ZnO薄膜具有更低的本底载流子浓度,这将为日后通过降低自补偿实现p型掺杂提供一个很好的解决办法。