Modelling of the QWSC is performed using the device simulator, Simwindows [8-9]. Simwindows incorporates interactive solvers for electrical, optical and thermal equation sets. The electrical model uses the drift diffusion equations, the two dimensional density of states in the quantum wells, thermoionic emission at the quantum well interfaces and thermoionic emission and tunnelling across abrubt interfaces between wells and bulk materials. This quantum well model is presently limited to the inclusion of only the lowest of each electron and hole energy levels, which are estimated from analytical expressions for a finite height well rather than a solution of Schrodinger’s equation [10].

The simulated control cell is AlGaAs p-i-n solar cell with material and device parameters listed in table(1).

Table (1) Material and device parameters of AlGaAs p-i-n control cell.

are increased in the active region within the intrinsic region with different barrier to well width ratio between 1 to 0.25 and spacer thickness between 100 and 300 A. In both cases the target is to optimize all parameters in order to maximize the cell efficiency.