Diamond is a unique semiconductor material with exceptional intrinsic properties that make it highly attractive for high-power, high-frequency, and high-temperature electronic applications. Its ultra-wide bandgap of 5.47 eV at room temperature is significantly larger than that of conventional semiconductors like silicon (1.12 eV) and even exceeds those of other wide bandgap materials such as silicon carbide (SiC, ~3.3 eV) and gallium nitride (GaN, ~3.4 eV). This large bandgap results in a high breakdown electric field, estimated to be around 10 MV/cm, which is an order of magnitude higher than SiC (2.5–3.5 MV/cm) and GaN (3.3 MV/cm). The high breakdown voltage allows diamond-based devices to operate at much higher voltages and power densities without undergoing avalanche breakdown.

Thermal conductivity is another standout property of diamond, reaching up to 2200 W/m·K for high-purity single crystals at room temperature. This value is nearly five times higher than that of copper and significantly surpasses SiC (490 W/m·K) and GaN (253 W/m·K). The exceptional thermal conductivity ensures efficient heat dissipation, which is critical for high-power electronic applications where thermal management is a limiting factor. The combination of high breakdown voltage and thermal conductivity positions diamond as an ideal material for devices operating under extreme conditions.

Charge carrier mobility in diamond is also remarkable, with theoretical electron mobility values exceeding 4500 cm²/V·s and hole mobility around 3800 cm²/V·s for high-purity samples. These values are higher than those of SiC (electron mobility ~900 cm²/V·s) and GaN (electron mobility ~2000 cm²/V·s). However, achieving these high mobilities in practice is challenging due to phonon scattering and defect-related limitations. At room temperature, phonon scattering dominates, reducing the mobility to around 2000 cm²/V·s for electrons and 1800 cm²/V·s for holes. Despite this reduction, diamond still outperforms many other semiconductors in terms of carrier transport efficiency.

The electronic structure of diamond is characterized by a direct bandgap at the Γ-point, but due to its large bandgap, intrinsic diamond is an excellent insulator with negligible free carrier concentration at room temperature. The valence band maximum is formed by sp³ hybridized carbon orbitals, while the conduction band minimum consists of antibonding states. The strong covalent bonding in diamond contributes to its high mechanical hardness and chemical stability, but it also means that introducing dopants to modify its electronic properties is more challenging compared to SiC or GaN.

Phonon scattering plays a significant role in diamond's thermal and electronic properties. The high Debye temperature of diamond (~2200 K) indicates strong covalent bonding and high phonon frequencies. Optical phonons dominate at high temperatures, leading to increased scattering rates for charge carriers. However, the high phonon group velocity in diamond contributes to its superior thermal conductivity. Theoretical studies using density functional theory (DFT) and molecular dynamics simulations have provided insights into phonon dispersion relations and their impact on thermal transport.

Achieving high-purity single-crystal diamond for electronic applications remains a major challenge. The presence of defects such as vacancies, dislocations, and impurities like nitrogen and boron can significantly degrade its electronic properties. Nitrogen is a common impurity in natural and synthetic diamond, forming deep donor levels at 1.7 eV below the conduction band. Even at concentrations as low as 1 ppm, nitrogen can act as a trapping center, reducing carrier mobility and lifetime. Boron, on the other hand, creates an acceptor level at 0.37 eV above the valence band, making diamond p-type when incorporated.

The synthesis of high-purity diamond typically involves chemical vapor deposition (CVD) techniques, where methane and hydrogen gases are dissociated in a plasma to deposit carbon atoms on a substrate. Optimizing growth conditions to minimize defects and impurities is critical. For instance, reducing nitrogen contamination requires ultra-high-purity precursor gases and careful control of the growth environment. Dislocations and grain boundaries in heteroepitaxial diamond films grown on non-diamond substrates further complicate the pursuit of high-quality material. Homoepitaxial growth on high-pressure high-temperature (HPHT) diamond seeds has shown better results but remains costly and limited in scalability.

Experimental studies on charge transport in diamond have revealed the importance of defect states and surface conductivity. Surface transfer doping, where adsorbates on the hydrogen-terminated diamond surface induce a two-dimensional hole gas, has been extensively investigated. However, intrinsic bulk properties are more relevant for high-power devices, necessitating defect-free material. Time-resolved photoconductivity measurements have provided data on carrier lifetimes, with values ranging from nanoseconds in defective material to microseconds in high-purity samples.

Comparing diamond to SiC and GaN highlights its superior intrinsic properties but also underscores the challenges in material synthesis and device fabrication. While SiC and GaN benefit from more mature growth techniques and commercial availability, diamond's extreme properties offer potential advantages for next-generation electronics. Theoretical models predict that diamond-based devices could outperform SiC and GaN in terms of power handling and efficiency, provided that high-quality material can be consistently produced.

In summary, diamond's ultra-wide bandgap, high breakdown voltage, exceptional thermal conductivity, and high carrier mobility make it a promising semiconductor for demanding applications. However, the difficulties in synthesizing high-purity single-crystal material with minimal defects and impurities remain significant barriers. Ongoing research into growth techniques, defect engineering, and fundamental charge transport mechanisms will be essential to unlock diamond's full potential in electronics.