热循环退火对InAs/Si(211)薄膜结构和电学性能的影响

InAs作为III-V族化合物半导体材料,可以应用于磁阻和霍尔元器件、量子点激光器元件、太阳能电池和红外探测器元件等方面,具有广泛的研究和应用前景.本文以Si(211)为衬底,采用热壁外延(hot wall epitaxy,HWE)技术制备了InAs薄膜,研究热循环退火(thermal cycle annealing,TCA)次数对InAs/Si(211)薄膜结构及电学性能的影响.热壁外延制备InAs薄膜的衬底温度为400℃,生长时间为4 h,不同的热循环退火次数为2、4、6、8、10.X射线衍射(XRD)测试表明:利用HWE技术在Si(211)衬底表面成功制备了闪锌矿结构的InAs薄膜,且沿(111)取向择优生长;TCA能够明显增强Si(211)衬底表面生长的InAs薄膜的择优取向.扫描电子显微镜(SEM)及原子力显微镜(AFM)测试分析表明:随着TCA次数增加到6次,InAs/Si(211)薄膜表面由于晶粒细化作用变得均匀平整,表面粗糙度从69.63 nm降低到56.43 nm,此时霍尔迁移率达到2.67×10~3cm~2/(V·s);过多的退火次数(≥8次)又会使薄膜表面的晶粒过大、缺陷增多,导致薄膜性能下降.

Effect of thermal cycle annealing on the microstructure and properties of InAs/Si(211) films

As a kind of III-V group compound semiconductor material, InAs can be applied to magnetic resistance and Hall devices, quantum dot laser devices, solar cells and infrared detector devices, etc, and show wide prospects for research and applications. High preferred orientation InAs films were prepared on (211) tilted single crystalline Si substrate by Hot Wall Epitaxy ( HWE) technique. The effect of thermal cycle annealing ( TCA) on the microstructure and electric properties of InAs films has been investigated in details. InAs films were prepared by hot wall epitaxy at substrate temperature of 400 ℃, deposition time of 4 h and different annealing cycles of 2, 4, 6, 8, or 10. The X-ray diffraction ( XRD ) results indicated that the zinc-blende structure of InAs films with highly preferred to (111)-direction was deposited on Si(211) substrate by HWE. Thepreferred orientation of InAs films on Si(211) substrates can be enhanced obviously by TCA treatment. Scanning electron microscopy and atomic force microscopy ( AFM ) observations showed that the as-deposited films are homogeneous and smooth with tincreasing the annealing cycles from 0 to 6. The AFM studies showed that surface roughness of InAs films are reduced from 69.63 nm to 56.43 nm with cycle annealing. Hall mobility of InAs/Si(211) film reached a value of 2.67×103 cm2/(V·s). However, the number of dislocations and the size of grain increase with an increase in the annealing cycles, leading to a reduced performance of the film.