Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 46: Poster 2

HL 46.10: Poster

Donnerstag, 29. März 2007, 15:00–17:30, Poster A

Characterisation of deep defects in undoped GaN layers with PICTS — •Carsten Baer, Hartmut Witte, Andre Krtschil, Armin Dadgar, and Alois Krost — Institut für Experimentelle Physik, Abteilung Halbleiterepitaxie, Otto-von-Guericke-Universität Magdeburg, 39016 Magdeburg

Undoped semiinsulating GaN layers are already commercially used in FET devices. The device performance of these FETs is strongly influenced by active deep defects which change essential parameters such as cut-off frequency, break down voltage, or temperature dependent behavior of the output characteristics.

In this contribution we describe in detail thermal emissions of deep defects and their dependence on excitation conditions in different highly resistive GaN layers analyzed by Photo-Induced Current Transient Spectroscopy (PICTS). All samples were grown by metal-organic vapor phase epitaxy on silicon or sapphire substrates.

All emission spectra below 300 K were influenced by different excitation wavelengths and intensities. The peak shift of some defects in the calculated spectra is found to be controlled by excitation parameters such as filling rate of the traps, the thermal capture rates, or the life times of the carriers, sometimes resulting in relatively high activation energies. Furthermore, we observe quenching behavior of traps induced by additional illumination with intrinsic light of 690nm. The PICTS spectra are compared with reference results from TSC and nano-DLTS measurements performed at the same samples.