Abstract
We investigate high electron mobility transistors (HEMT’s) based on AlGaN/GaN grown by molecular beam epitaxy on Silicon substrates. The improvement of the performances of such transistors is still subject to the influence of threading dislocations and point defects which are commonly observed in these devices. Deep levels in FAT-HEMT’s are characterized by using Capacitance-Voltage (C-V) measurements, from which we can extract the barrier height and the donor concentration in the AlGaN layer. Deep Level Transient Spectroscopy (DLTS) Technique is also employed to identify defects in the heterostructure. Measurements reveal the presence of one electron trap with the activation energy E1 = 0.30 eV and capture cross-section σn = 3.59 10–19cm2. The localization and the identification of this trap have been discussed.
Highlights
The material semiconductor GaN nitride and associated alloys (III-N compounds) arouse since more than three decades a regained interest because of their properties and their exceptional robustness [1,2,3]
We investigate high electron mobility transistors (HEMT’s) based on AlGaN/GaN grown by molecular beam epitaxy on Silicon substrates
We note that the capacitance variation as a function of the gate voltage shows the existence of a capacitance plateau appearing from 8 V to 2 V, and it is associated to the depletion of the two-dimensional electron gas (2-DEG), located at the heterointerface
Summary
The material semiconductor GaN nitride and associated alloys (III-N compounds) arouse since more than three decades a regained interest because of their properties and their exceptional robustness [1,2,3]. A new market emerges in the field of telecommunications with High Electronic Mobility Transistors (HEMT’s) which can support power densities 10 times higher than those accessible with the silicon and gallium arsenide technologies as reported by Dumka et al [6], as well as cut-off frequencies higher than 100 GHz were reported in a previous paper [7] These HEMT’s structures are essential to meet the increasing needs for the communication systems requiring high power and frequency applications [8,9,10] (radars, stations of bases, connection satellite). We will characterize the electrical active defects present in the structure, using DLTS This technique has been proved to be a powerful tool to probe the electronic properties of FAT-HEMT AlGaN/GaN transistors. The localization and the identification of these traps are discussed
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