Simulation And Design Of InGaN Solar Cells

Indium Gallium Nitride (InGaN) solar cells, as one new type of semiconductor solar cells, have led to one of the promising research areas on the III-group nitrides and photovoltaic devices all over the world. Comparing with traditional photovoltaic materials and devices, however, the study on full-solar-spectrum high-efficiency InGaN cells is still insufficient, leaving many problems unsolved in the structure design. In order to obtain a good performance for InGaN solar cells, we must pay attention to the design of the chip architecture.By using a semiconductor device simulator Silvaco TCAD, this thesis focuses on the modeling of InGaN solar cells, We take the examples of the silicon solar cells and other III-group nitrides as references when we select physical models. Based on the different structures of InGaN solar cells, we compare the simulation results and optimize the design of architure so as to obtain the InGaN solar cells with high efficiency. In the thesis, we have also constructed models for different types of InGaN solar cells, such as PN, PIN and multiple-quantum-wells (MQWs) solar cells, and different parameters were analyzed which affect the efficiency of InGaN solar cells.In order to get higher external quantum efficiency, we propose that the In-content of the absoption region of InGaN solar cells should get close to 0.6, and the In-content determines absorption range of InGaN solar cells. The In-content between each layer should be lower than 0.3, otherwise the transmission efficiency of heterojunction will be bad.In order to get higher internal quantum efficiency, we propose that the thickness of P-type region should be thinner than 50 nm, and 110 nm for the N-type region. The length of the depletion region should be around 300 nm, and it should be placed close to the top of the cell, the doping of P and N regions must be higher than 1.0×1018 per cc. In the MQWs solar cells, the width of the quantum wells should be around 3 nm,so as to increase the short-circuit current.Taking advantage of the obtained simulation data, we propose three optimized designs for the three types of InGaN solar cell and the achievable efficiency is up to 23.5%, 32.1% and 31.4%, respectively.