Investigation of anomalous conductive channel at AlN/Silicon interface

Owing to a vital combination of wide band gap, high electron saturation velocity, and ultralow channel resistance, AlGaN/GaN high electron mobility transistors (HEMTs) are of great interest for the next generation of high frequency telecommunication and power switching applications. Although such devices are to benefit from large-area availability, low-cost, and fabrication maturity of silicon, extreme challenges in direct epitaxial growth of GaN-on-Si resulting from high lattice mismatch and large thermo-elastic strain has led to the use of intercalating AlN nucleation layers between Si and GaN/Al(Ga)N based buffer layers. Thanks to this nucleation layer, a significant improvement in the structural quality of grown Al(Ga)N buffer layers has finally been achieved. On the downside, nucleation layer is also considered the prime candidate for introducing a conductive channel at AlN/Si interface leading to significant power loss.

This internship aims toward understanding the origin of propagation losses in GaN-on-Si HEMTs at microwaves frequencies, which are critical for efficient devices and circuits. In order to understand the physical origin and location of conductive channel at AlN/Si interface, the intern will make use of scanning probe microscopies, mainly scanning spreading resistance microscopy and scanning capacitance microscopy. From the two techniques, the intern shall be able to quantitatively determine unintentional doping depth-profiles in Silicon substrate. This in addition with the external SIMS data will facilitate further chemical analysis. With the guidance of his/her supervisor, data interpretation and analysis will also be a major part of the thesis/internship. As such, the intern will be guided in design of the experiment and understanding the resulting experimental data. A good command of English is required.