246nm p-i-n型背照AlGaN太阳盲紫外探测器的研制

设计并制备出短波长p-i-n型背照AlGaN太阳盲紫外探测器,响应波段为225～255 nm,峰值波长为246nm。材料为在蓝宝石衬底上生长的背照式p-i-n型异质结结构,n型窗口层的AlxGa1-xN中的Al组分为71%,非故意掺杂吸收层中的Al组分为52%。零偏压下测得的暗电流为27 pA,光电流为2.7 nA,峰值响应度为23 mA/W。并在此基础上制备出大面阵太阳盲紫外探测器芯片,其像元数为128×128,光敏元直径为44μm,像元间距为50μm。

Ni基电极淀积前后表面处理对p-GaN欧姆接触的影响

在p-GaN上蒸发Ni/Au电极前,采用王水、HCl、缓冲HF进行前表面处理,O2气氛下退火后,比较各电极样品的I-V特性和表面形貌。结果显示无表面处理时接触电阻最小,且溶剂处理后残留的电解质会影响电极的电流特性和稳定性。用俄歇电子能谱(AES)测试不同元素随深度分布情况,发现高温退火过程中NiO的形成有自动清洁p-GaN表面的作用,因此对于Ni基电极前表面处理不是必需的。再将样品用10%草酸溶液处理,其I-V特性显示接触电阻率明显下降;X射线光电子能谱(XPS)测试显示草酸溶液处理后电极表面Ni含量显著减少,而Au元素信号峰增强,说明表面高阻p型NiO被有效除去,对改善接触性能具有实际意义。

采用双甲技术改进净化工艺

文中提出几个双甲技术方案以改进净化工艺,经比较并结合该厂实际推荐双联醇塔串甲烷化的方案。

NiO removal of Ni/Au Ohmic contact to p-GaN after annealing

The Ni/Au contact was treated with oxalic acid after annealing in 02 ambient, and its 1-V characteristic showed the property of contact has been obviously improved. An Auger electron spectroscopy （AES） depth profile of the contact as-annealed showed that the top layer was highly resistive NiO, while an X-ray photo-electron spectroscopy （XPS） of oxalic acid treated samples indicated that the NiO has been removed effectively. A scanning electron microscope （SEM） was used to observe the surface morphology of the contacts, and it was found that the lacunaris surface right after annealing became quite smooth with lots of small Au exposed areas after oxalic acid treatment. When the test probe or the subsequently deposited Ti/Au was directly in contact with these small Au areas, they worked as low resistive current paths and thus decrease the specific contact resistance.