Fig. 9

a Relationship between suitable doping level and thickness of charge layer (APD-1). The thickness of charge layer is 50 nm (black square), 90 nm (black circle), 130 nm (black triangle), 170 nm (black down-pointing triangle), 210 nm (black diamond). a presents the suitable doping level region for different thickness of charge layer. As the charge layer thickness increases, the suitable doping level range in the charge layer decreases. A relatively large doping level range exists in the thin charge layer, and under this doping level range, the device will have a suitable electric field distribution. Apparently, the doping level range is determined by charge layer thickness. b Relationship between suitable doping level and thickness of charge layer (APD-2). The thickness of charge layer is 50 nm (black square), 70 nm (black circle), 90 nm (black triangle), 110 nm (black down-pointing triangle), 130 nm (black diamond), and 150 nm (black pentagon). The figure description of b is similar to a. c Comparison of calculated results in Fig. 2 and simulated results in Fig. 9b. Dashed line: calculated results. Closed symbols: simulated results (black square). c presents the comparison of calculated results in Fig. 2 and simulated results in Fig. 9b. The calculated results and simulated results correspond well