为了实现低电阻率厚度为纳米级的红外探测器电极材料,通过离子注入的方法将高浓度的As掺入高阻单晶硅,并经过快速退火处理,获得了厚度∼200 nm、电阻率为10-4Ω·cm的Si：As电极层.原子力显微镜测试结果表明,离子注入的样品表面依然较平整,表面均方根粗糙度仅为0.5 nm.使用聚焦离子束设备(FIB)制备高分辨透射电镜(HRTEM)样品,高浓度的As掺入虽然会损伤Si晶格、引入大量的缺陷,但是HRTEM观察表明合适的退火工艺能够使得完整晶格得到恢复,而且霍尔效应和扩展电阻的测量分析表明,用离子注入方法制备的Si：As层载流子浓度达到2.5×1020 cm-3、电子迁移率高于40 cm2/V·s,具有优异的电学性能,适合用作各种Si基光电器件的背电极.%To achieve nanoscale infrared photodetector electrodes with low resistivity, ion-implantation is used to implant high dose of As ion into high-resistivity silicon, and followed by rapid thermal annealing (RTA). A 200 nm thick Si:As layer with resistivity of 10−4 Ω·cm is obtained. Characterization by atomic force microscopy shows that the surfaces of the ion-implanted samples are smooth with a root-mean-square (RMS) coarseness of 0.5 nm. Although introduction of As ions destroys the lattice structure of crystalline silicon and causes a plenty of defects, proper annealing can restore the crystal lattice, as evidenced by the HRTEM observation of the annealed sample prepared by using focused ion beam (FIB) technology. Besides, the measurements of hall effect and spreading resistance indicate that the Si:As layer has good electrical properties including high carrier concentrations 2.5 × 1020 cm−3, high electron mobilities 40 cm2/V·s, and high electrical conductivities. The low resistivity Si:As material obtained is suitable to be used as the back electrodes of silicon-based optoelectronic devices.
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