Boron Nitride Fabrication Techniques and Physical Properties

The III-nitride semiconductors are known for their excellent extrinsic properties like direct bandgap, low electron affinity, and chemical and thermal stability. Among III-nitride semiconductors, boron nitride has proven to be a favorable candidate for common dimension materials in several crystalline forms due to its sp2- or sp3-hybridized atomic orbitals. Among all crystalline forms, hexagonal (h-BN) and cubic (c-BN) are considered as the most stable crystalline forms. Like carbon allotropes, the BN has been obtained in different nanostructured forms, e.g., BN nanotube, BN fullerene, and BN nanosheets. The BN nanosheets are a few atomic layers of BN in which boron and nitrogen are arranged in-planer in hexagonal form. The nanostructure sheets are used for sensors, microwave optics, dielectric gates, and ultraviolet emitters. The most effective and preferred technique to fabricate BN materials is through CVD. During the growth, BN formation occurs as a bottom-up growth mechanism in which boron and nitrogen atoms form a few layers on the substrate. This technique is suitable for high quality and large-area growth. Although a few monolayers of BN are grown for most applications, these few monolayers are hard to detect by any optical means as BN is transparent to a wide range of wavelengths. This chapter will discuss the physical properties and growth of BN materials in detail.