Defects and Dopants in Wide-Bandgap Semiconductors

Abstract

Wide-bandgap (WBG) semiconductors, such as silicon carbide (SiC), gallium nitride (GaN), diamond, and aluminum nitride (AlN), have emerged as critical materials for next-generation electronic and optoelectronic devices due to their superior thermal stability, high breakdown voltage, and wide energy bandgaps. However, intrinsic and extrinsic defects, as well as the incorporation of dopants, significantly influence their electrical, optical, and mechanical properties. This paper provides a comprehensive review of the role of defects and dopants in WBG semiconductors, addressing their fundamental physics, experimental characterization, and impact on device performance. Intrinsic defects, including vacancies, interstitials, and antisite defects, alter charge carrier dynamics, while extrinsic dopants introduce impurity levels that control conductivity and carrier mobility. The efficiency of p-type and n-type doping is often hindered by self-compensation mechanisms, limiting charge carrier activation. Advanced characterization techniques such as photoluminescence (PL) spectroscopy, deep-level transient spectroscopy (DLTS), and electron paramagnetic resonance (EPR) provide insights into defect states, their electronic structure, and their effects on semiconductor behavior. The impact of defects on electrical conductivity, luminescence efficiency, and thermal properties is discussed in the context of various applications, including power electronics, deep-UV optoelectronics, and quantum technologies. Special attention is given to nitrogen-vacancy (NV) centers in diamond and single-photon emitters in WBG semiconductors, which hold promise for quantum computing and communication. Despite recent advances, several challenges remain, including precise defect control during material growth, achieving efficient dopant activation, and mitigating unintentional defects. Future research directions, such as AI-driven defect modeling and novel doping strategies, are explored to enhance the functional capabilities of WBG semiconductors. This study aims to bridge the gap between theoretical models and practical applications, paving the way for more reliable and efficient semiconductor devices.