Rich Device Physics Found in Photoresponses of Low-Dimensional Photodetectors by Fitting With Explicit Photogain Theory

In this work, we employed our newly established explicit photogain theory to probe physics in nanodevices at single device level. A single fitting of the explicit photogain theory to experimental photoresponses allows us to find important device parameters including surface depletion region width W_dep, doping concentration N_A (or N_D), carrier mobility $\mu _{\text{p}}$ (or $\mu _{\text{n}}$ ), minority recombination lifetime $\tau _{0}$ and surface recombination velocity V_srv. These parameters are often difficult to calibrate using traditional semiconductor characterization techniques as the size of semiconductor devices scales down. The extracted parameters were verified with independent Hall effect measurements and other experiments. It shows that this technique is simple, nondestructive and accurate enough to probe the physics in nanodevices at single device level.