MOVPE, processing and characterization of AlGaN/GaN HEMTs with different Al concentrations on silicon substrates

AlInN/GaN HEMTs on sapphire: dc and pulsed characterisation

“…However, testing the device under class-B bias point, no appreciable improvement of the dispersion effects can be seen. This is in contrast to our former observations concerning AlInN/GaN HEMTs pulsed under the same conditions [6]. However, the samples reported there had an additional 5 nm GaN cap, which may significantly affect the surface properties and the interaction with the SiN passivation.…”

“…Dispersion effects of the AlInN/GaN system are still in an early stage of investigation. First results indicate no or at least reduced dispersion compared to AlGaN-based devices [5,6]. It is still to be clarified if this is related to fundamental properties of the AlInN surface as such or to specific material properties like residual doping in the barrier layer shielding the channel from the surface states.…”

Aluminium incorporation in AlxGa1−xN/GaN heterostructures: A comparative study by ion beam analysis and X-ray diffraction

“…In fact the use of one or multiple HS of the (Al,Ga,In)N system has led to present visible and UV light emitting diodes and laser diodes, to Bragg reflectors, superlattices, high electron mobility transistors (HEMT), UV photodetectors, resonant tunnelling diodes, etc. [1,2]. In the case of GaN HEMT a single AlGaN/GaN HS forms a triangular quantum well that host a high-density two dimensional electron gas (2DEG) at the GaN side, that shows excellent transport properties along the AlGaN/GaN interface [1][2][3].…”

“…[1,2]. In the case of GaN HEMT a single AlGaN/GaN HS forms a triangular quantum well that host a high-density two dimensional electron gas (2DEG) at the GaN side, that shows excellent transport properties along the AlGaN/GaN interface [1][2][3]. In this way, both higher carrier velocities and total electron density have been achieved [3].…”

“…In the case of a basic GaN HEMT, tailoring the electrical properties of the AlGaN/GaN HS depends mainly on the AlGaN barrier thickness, typically in the order of 30 nm, and on its Al content (usually in the 0.2 range) [2,3]. The impact of these variables may also be convoluted with the parallel development of strain within the layer, since the AlGaN layer starts growing pseudomorphic to the GaN substrate and then relaxes after reaching a critical thickness [2].…”