Bandgap engineering in III-nitrides with boron and group V elements: Toward applications in ultraviolet emitters

Abstract

A key material system for opto- and high-power electronics are III-nitrides. Their functionality can be expanded when bandgap engineering is extended beyond common materials such as AlN, GaN, and InN. Combining these three compounds with boron nitride and other III–V compounds (GaP, GaAs, GaSb, InP, etc.) is an intuitive method of expanding bandgap engineering in semiconductor devices. This may allow improvement of current devices for which performances are limited by the intrinsic properties of common III-nitride alloys, as well as the creation of novel devices. A comprehensive review of this activity is presented in this article, including an up-to-date compilation of material parameters for wurtzite boron nitride; its alloying with other III-nitrides, including structural and optical characterization; the band anticrossing model for III-nitrides diluted with group V atoms; their synthesis and structural and optical characterization; and examples of applications of III-nitrides containing boron and group V atoms in semiconductor devices. It is shown to be very beneficial for ultraviolet emitters to incorporate alloying of III-nitrides with BN, as these compounds have lattice constants much smaller than that of AlN, offering unique possibilities in strain engineering. It is shown that the incorporation of P, As, Sb, and Bi in GaN is low when the material is deposited at this temperature, which is optimal for the host. Lowering the growth temperature significantly enhances the incorporation of isovalent dopants, but deteriorates the optical quality of the material. The obtained changes in the electronic band structure can be beneficial in many applications, including water splitting or shifting emission toward longer wavelengths.