The Preparation, Optical And Electrical Properties Of A-Si:H(nc-Si:H)/a-SiC:H Multilayer Films

The a-Si:H/a-SiC:H multilayer film was prepared on the monocrystalline silicon andquartz substrates by radio frequency plasma enhanced chemical vapor deposition technique(RF-PECVD), using SiH4,CH4and H2as reaction gas sources. The nc-Si:H/a-SiC:Hmultilayer films were annealed at high temperature. The microstructures ofa-Si:H(nc-Si:H)/a-SiC:H samples characterized represented using transmission electronmicroscope(TEM), X-ray diffractometer(XRD), Raman spectroscopy, as well as Fouriertransform infrared spectroscopy(FT-IR) testing instruments. At the same time, the optical andelectrical properties of a-Si:H(nc-Si:H)/a-SiC:H mutilayer films were experimental studied.The results show that the multilayer film samples have good periodic structure and steepinterfaces. Size-controlled Si nanocrystals in well layer of a-Si:H were prepared by annealingat high temperature. At room temperature, sequential resonant tunneling peculiarities on thevertical direction of unannealed multilayer samples were observed, carriers’ transport ofannealed samples correspond to Fowler–Nordheim(FN) tunneling mechanism at high electricfield.The optical band gap increase and optical absorption coefficient decrease with thedecreasing of well layer thickness, which reasult from quantum size confinement effect, butthere is no obviously change in the opical absorption coefficient and band gap ofnc-Si:H/a-SiC:H mutilayer film with the decreasing of barrier layer thickness. In addition,when the samples were annealed at450℃,the optical band gap of mutilayer samples decreasewith increasing of defect density, which rseults from H atoms escaped from samples. Whenthe samples were annealed at900℃,quantum confinement effect is enhanced beacause of Sinanocrystals presented in well layer, the optical band gap of samples is increased.