Vacuum High Temperature Oven with Graphitic Isolation

高温退火（HTA）的高缺陷（~ 1011 cm-2）的蓝宝石衬底上的电沉积AlN层最近被证明是一个有前途的方法，减少缺陷。AlN被证明是少数几种可以在高温下退火而不离解的化合物掺杂剂之一，类似于硅。在缺陷退火过程中，溅射层被加热到高达1750 °C的温度。到目前为止，在高温退火期间主要使用氮气气氛。同时，有明确的实验指示，由相图考虑支持，在反应性气体气氛（例如CO或NH3）下的退火步骤可以导致AlN的稳定化，从而使得在甚至更高的温度下退火成为可能。高温热处理工艺的目标是进一步提高晶体质量。因此，我们建议购买带有石墨加热器和石墨隔热材料的高温真空炉。计划中的工作不仅从科学的角度来看是有趣的，而且将为更高效的UV-LED以及氮化物基功率电子器件提供一种使能技术，其中漏电流对螺旋位错的密度敏感。总的来说，建议的熔炉应提供反应性气体气氛（H2、CO、NH3）和惰性/反应性气体混合物，温度至少达到1750 °C。

The high temperature annealing (HTA) of highly defective (~ 1011 cm-2) sputter-deposited AlN layers on sapphire substrates recently turned out to be a promising method for defect reduction. AlN proved itself as one of the few compound semicondutors that can be annealed at high temperatures without dissociation, similiar to silicon. During the defect annealing process, the as-sputtered layers are heated to temperatures up to 1750 °C. So far, mostly nitrogen atmospheres are used during high temperature annealing. Meanwhile, there are clear experimental indications, backed by phase diagram considerations, that an annealing step under reactive gas atmosphere e.g. CO or NH3 may lead to stabilization of the AlN and thus makes annealing at even higher temperatures possible. The HTA process at higher temperatures targets for an further increase of crystal quality.Therefore, we propose the acquisition of a high temperature vacuum furnace with a graphite heater and a graphite thermal insulation. The planned work is not only interesting from a scientific point of view, but would result in an enabling technology for more efficient UV-LEDs as well as nitride-based power electronics, where leakage currents react sensitive to the density of screw dislocations. Overall, the proposed furnace should offer reactive gas atmospheres (H2, CO, NH3) and inert/reactive gas mixtures at temperatures up to at least 1750 °C.