Volume 3, Number 1, 2000, 57 - 62


Hydrogenation of Pseudomorphic Hemt Structures

M. Lagadas, M. Androulidaki, M. Kayiambaki,
G. Constantinidis, K. Michelakis, Z. Hatzopoulos
Foundation for Research and Technology-Hellas(FORTH),
IESL, Microelectronics Research Group, P.O.Box 1527,
71110 Heraklion, Crete, Greece

S. Mikroulis
Physics Department, University of Crete,
P.O. Box 2208, GR-71003 Heraklion, Crete, Greece

E.C. Paloura, J. Kalomiros
Aristotle University of Thessaloniki,
Department of Physics, GR-54006, Greece

We have investigated the effects of hydrogenation in AlGaAs/InGaAs/GaAs PM-HEMT structures. A hydrogen glow discharge was used for the hydrogenation of the structures at a pressure of 150mTorr for time duration from 15 min up to 4 hours and sample temperature ranging from 45o C to 200o C. Degradation of the electrical performance has been observed.A gradual reduction of the saturation current IDSS and the transconductance gm of the devices as a function of the hydrogenation time was detected. Moreover, a shifting of gm vs the gate-source voltage Vgs at higher voltages has been observed. The degradation of the electrical performance of the devices is attributed to the passivation of Si donors in the AlGaAs layer of the structure. Deep Level Transient Spectroscopy revealed a partial passivation of DX related centers in the AlGaAs layer while Photoluminescense characterization showed improvement in the quantum-well characteristics (lower FWHM and higher peak intensity).