Frequency dispersion investigation of output reactance and capacitance in GaAs MESFETs by means of dielectric loss tangent consideration

The aim of this article is to investigate the effect of dielectric loss tangent on frequency dispersion of output reactance and capacitance in GaAs MESFETs. For this purpose, measurements of output impedance modulus and phase have been carried out within a frequency range of 10 Hz to 10 kHz, and various voltage values of gate-source (V_gs=0, -0.2, -0.3, -0.35, -0.4, -0.45, -0.5 and -0.6 V) and drain-source (V_ds=0.7, 0.9, 1, 1.5 and 2 V) Based on the concept of complex permittivity of semiconductor material, complex capacitance is used to analyze and simulate frequency dispersion of output reactance and capacitance of GaAs MESFETs. The results show that conductor losses which dominate the dielectric loss tangent are attributed to trapping mechanisms at the interface of devices; so they influence the frequency dispersion of output reactance and capacitance in particular at low frequencies. This reveals that frequency dispersion of these parameters is also related to dielectric loss tangent of semiconductor materials which affects the response of electronic devices according to frequency variation.