A computer simulation model of p +(a-Si:H)/n(c-Si) heterojunction solar cells at thermodynamic equilibrium using a Scharfetter-Gummel solution of Poisson's equation has been developed.The results indicate that the design of thinner p +(a-Si:H) layer is employed to effectively increase the collection and transport of photo-generated carriers,enhancing the performances of a-Si/c-Si heterojuncion solar cells.Also,the influence of p-type dopping concentration in p +(a-Si:H) thin film on the collection and transport of photo-generated carriers in p +(a-Si:H)/n(c-Si) heterojuncion solar cells is discussed.Under the condition of prolonged light soaking,the simulation shows that a-Si/c-Si heterojuncion structure solar cell possesses high light stability.