Fabrication And Characteristic Of A-Si:H(P)/c-Si(N) Heteroj Unction On Silicon Substrate

Hydrogenated amorphous silicon (a-Si:H) is considered very important materials in device application field, and battery made of crystalline silicon material has been the leading product in the market of PV (Photovoltaic). In order to make full use of a-Si:H and c-Si excellent characteristics, a-Si:H/c-Si heterojunction has been extensively researched about electronic and optical properties. Heterojunction solar cells of a-Si:H and c-Si are promising candidates, because it combines the merits of c-Si solar cells and the a-Si:H production techniques. This structure has a lot of advantages:1) rectifing characteristics is very good, and within the larger reverse bias range only has a very small dark current;2)the electron-hole pairs spread to produce the photocurrent under reverse bias in the depleted region;3) heterojunctions are synthetized at low temperature, and this process can prevent the formation of internal defects of crystalline silicon in some extent.This paper describes the preparation methods and characterization of planar and radial heterojunction. The method of the preparation plane heterojunction is deposited amorphous silicon thin film on the n type (100) monocrystalline silicon substrate through the hot wire chemical vapor deposition (HWCVD). The characteristic of the heterojunctions are analysed by changing the film thick and doping concentration. IV test result of the heterojunctions are compared, fitted and parameters extracted by two-diode model. The optimum experimental conditions are obtained. CV analysis get built-in potential and barrier height.The n type (100) monocrystalline silicon substrate is selected for preparation of radial heterojunction. The uniform array silicon nanowires are etched by the metal catalytic chemistry solution method. Then p type amorphous silicon film is deposited on n type single crystalline SiNWs by HWCVD that formed core-shell radial pn junction structures. Test results show that the nanowire radial structure has very strong antireflection property and the reflectivity is lower than2.5%in broad spectral range. The dark IV curve is measured and compared with the simulation results based on the two-diode model. According to the lnl-V curve trend, curve is devided into four parts. The parameters are extracted respectively by the different role of each part. Extract parameters including:reverse saturated current, diode ideal factor, series resistance and parallel resistance.