Frequency dispersion of transconductance: a tool to characterise deep levels in III-V FETs

Frequency dispersion of transconductance g m (f) has been exploited to quantitatively investigate the properties of deep traps in III-V FET devices, namely DX centres in GaAs/AlGaAs HEMTs. This method requires simple data acquisition and elaboration and is applied directly to packaged devices. Thermal emission energy E a =0.46 eV and capture cross-section σ=3.10 -14 cm 2 have been obtained for DX centers in AlGaAs, in good agreement with published data. By increasing V DS , we measured also an E n decrease due to hot electron trapping by the DX centres