• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.10
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• pp.678-686
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• 2001

Origins for the transconductance dispersion and the gate leakage current in a GaAs metal semiconductor field effect transistor were found using capacitance deep-level transient spectroscopy (DLTS) measurements. In DLTS spectra, we observed two surface states with thermal activation energies of 0.65 $\times$ 0.07 eV and 0.88 $\times$ 0.04 eV and an electron trap EL2 with thermal activation energy of 0.84 $\times$ 0.01 eV. Transconductance was decreased in the frequency range of 5.5 Hz ~ 300 Hz. The transition frequency shifted to higher frequencies with the increase of temperature and the activation energy for the change of the transition frequency was determined to be 0.66 $\times$ 0.02 eV. From the measurements of the gate leakage current as a function of the device temperature, the forward and reverse currents are coincident with each other below gate voltages lower than 0.15 V, namely Ohmic behavior between gate and source/drain electrodes. The activation energy for the conductance of electrons on the surface of MESFET was 0.63 $\times$ 0.01 eV. Comparing activation energies obtained by different measurements, we found surface states H1 caused the transconductance dispersion and the fate leakage current.