Two-factor Optimization And Electrical Properties Of Microcrystalline Silicon Thin Film Deposition

The goal of this article is to increase the deposition rate of hydrogenated microcrystalline silicon(μc-Si:H). On the basis of the reseach of the influence of single deposition parameter on deposition rate, The deposition parameter ofμc-Si:H films were optimized by two factors, power density versus deposition pressure and silane concentration versus total flow rate ,by very high frequency plasma enhance chemical vapor deposition(VHF-PECVD). Meanswhile, we have researched the electronic property and the conductivity behavior of thin films. The device grade film that dark conductivity was 1.6×10^-8(Ωcm)^-1 and photosensitivity was 678 was finally prepared at rate of 2.1nm/s.It shows that:1. Under the condition of higher deposition pressure, high-speed high-qualityμc-Si:H can be prepared by use of high-pressure depletion, but the influence of power density and deposition pressure on the deposition rate weaken, in order to further enhance the deposition rate other deposition parameters must be changed.2. Under high deposition pressure condition, the use of higher silane concentration and smaller silane gas can rapidly prepareμc-Si:H, and get high gas utilization.3. Microcrystalline silicon thin films by high-speed preparation have a thick incubation layer. The vertical structure of thin films were studied by using step-by-step deposition of silane concentration based on the two-factor phase diagram of silane concentration versus gas total flow.4. The electrical property and the conduction behavior ofμc-Si:H were researched and analyzed by use of grain boundary barrier model and the statistics of Fermi level shift model respectively. The results show that: films in line with the requirements of solar cell active layer is located in the amorphous / microcrystalline transition zone, the film of the transition zone follow the Meyer-Neldel compensation rate, and the calculated value of characteristic energy of the MNR was about 61.3meV.5. In the two factors phase diagram of silane concentration—gas total flow, the optimization of the conditions are as follows: under the conditions of silane concentration of 4.5% and gas total flow of 100sccm, thin film deposition rate was 1.42nm/s, crystallization was 35%, dark conductivity was 8.7×10^-8 (Ωcm)^-1, conductivity activation energy was 0.47eV.6. The device grade film that dark conductivity was 1.6×10^-8(Ωcm)^-1 and photosensitivity was 678 was finally prepared at rate of 2.1nm/s under 600Pa.