Evaluation of Effective Device Parameters by Comparison of Measured and Simulated C-V Characteristics for Conventional and Pseudomorphic HEMTs

Measurements of the gate C-V characteristics of several conventional and pseudomorphic high electron mobility transistors (HEMT) on wafer and the comparison with simulations are presented. In order to study the influence of important technological parameters on the capacitance, the Schrodinger and Poisson equations were solved self-consistently in the structure, using the thickness of the doped layer d A , the doping density No and the built-in voltage Vb as fit parameters. Measurement and simulation were found to be in good agreement and the fit parameters can be shown to be the effective device parameters. We demonstrate how to apply this technique for monitoring the spatial variation of d A , N D and Vb over the wafer, a result of particular importance for the development of the manufacturing process and for calibrating the design of the device.