Investigation of Surface Charging Effects in AlGaN/GaN HEMT by a New Measurement Method

A new measurement method was confirmed that it was available to investigate the current collapse in AlGaN/GaN HEMT due to the surface trapping process of electrons. A characteristic time constant of the trapping process t
_p

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was defined and obtained to be about 0.38s in a specially designed HEMT by this method. We observed an abnormal trapping time resulting from the transport of the trapped electrons and demonstrated that there was a dynamic equilibrious distribution of the charged surface states when the bias stress is applied longer than t
_p

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