Structural and electrical characterization of thick GaN layers on Si, GaN, and engineered substrates

Abstract

A major challenge in gallium nitride (GaN) vertical power devices and other large bandgap materials is the high defect density that compromises the performance, reliability, and yield. Defects are typically nucleated at the heterointerface where there are both lattice and thermal mismatches. Here, we report the selective area growth (SAG) of thick GaN on Si and on the newly available Qromis Substrate Technology™ (QST) substrates that lead to a significant reduction of the defect densities to a level that is nearly comparable to that on native substrates by defect annihilation. We performed a parametric study of the electrical properties of the SAG GaN layers by fabricating and characterizing Schottky barrier diodes for SAG GaN layer thicknesses of 5, 10, 15, and 20 μm for GaN-on-Si, GaN-on-QST, and GaN-on-GaN diodes. While thicker layers led to a significant reduction in defect densities and improvement in the diode forward current characteristics, the GaN-on-QST diodes exhibited nearly similar characteristics to the GaN-on-GaN diodes. Further improvement in the device structure and/or SAG growth for GaN-on-Si is needed to achieve a comparable performance as the defect densities in the GaN-on-Si are comparable to that of GaN-on-QST substrates.

Simulation study of the tunnel junction position effect on the parameters of the InxGa1-xN dual junction solar cell

“…Modifying the indium content in InGaN alloys leads to modifying their electrical and optical properties. It is possible to grow multiple layers with different band gaps, with lattice-matched, and then with different properties [7][8][9][10][11]. In x Ga 1-x N alloys have many advantages: They have direct electronic band gaps, which make them efficient devices in the optoelectronic domain, and a large range of band gaps that extend from 0.7 eV for In to 3.4 eV for GaN, making them capable of converting most solar spectrum [11][12][13][14][15].…”

Effects of heavy Si doping on the structural and optical properties of n-GaN/AlN/Si(111) heterostructures

“…The large mismatch in lattice constants and thermal expansion coefficients between GaN and Si result in a very high density of crystal defects that strongly degrade devices performance. For this reason, the study of growth mechanisms and processes that improve the GaN epitaxial quality is a subject of current interest [5]. Early in the 90´s, Watanabe et al proposed the use of an AlN intermediate layer to avoid the formation of amorphous SiN at the GaN/Si interface due to the strong chemical reactivity between Si and N [6].…”

Challenges of Overcoming Defects in Wide Bandgap Semiconductor Power Electronics

“…(2) How does this information ultimately influence the electrical properties and performance of the materials and devices in extreme environments? The response to the first question is to identify and eliminate the root cause, namely, the lattice defect itself as it originates at interfaces, surfaces, and bulk regions [7][8][9]. This is a problem of manipulating the material structure as the material is being synthesized.…”