AlxGa(1-x)N\GaN structure diagnostic by C-V characteristics method

Nondestructive diagnostic method was developed for epitaxial heterostructure quality prediction. Such prediction is very important for production of some types HF FETs. The various heterostructure modifications grown on sapphire substrates have been analyzed. These structures were grown by MOCVD method from the metalorganic compounds with variation of Al mol-content in the AlGaN layers in wide limits (0,05>x>0,42). The C-V measurements were used for electrical analysis Al x GaN\GaN films with Hg-probe at frequencies 1MHz, 10kHz, 1kHz, 100Hz. Both electrodes (Hg-probe and Common) were placed on the same active surface of the heterostructure. C-V curves looks like a > with C max and C min independent of voltage. The test FETs were produced for comparison with results of C-V measurements. It was found that the voltage of transition from C max to C min corresponds with pinch-off voltage (V p.f. ) of test FETs. The values of C min > 1pF points to the presence of parasitic conducting layer in buffer layer.