INVESTIGATION OF POLARIZATION IN HETEROSTRUCTURES WITH THE QUANTUM WELL AlGaN / GaN USING CAPACITANCE-VOLTAGE CHARACTERISTICS

In the present study, the degree of relaxation of tension in the barrier layer of heterostructures AlGaN / GaN on the basis of measurements of the capacitance-voltage characteristics GaNHEMT is determined. Samples were grown on Al2O3 substrates by deposition of organometallic compounds from a gaseous phase. In order to conduct capacitance-voltage measurements, dualgate HEMT were created for all these tested HEMT-structures. From the measured capacitance voltage haracteristics, the Pexp polarization value within each HEMT-structure was obtained. By analyzing the capacitance-voltage characteristics, electron traps were found. According to the modified model by Ambacher, spontaneous Psp values and piezoelectric polarization Ppz were alculated. Obtained values Pexp, Psp and Ppz for each HEMT-structure allowed to determine the value of the relaxation degree of tension R in the barrier layer. Thus, the possibility of application of the capacity-voltage characteristics for evaluating the quality of the crystal structure of the barrier layer in the heterostructure AlGaN / GaN is shown