# A Near-Ultraviolet Photodetector Based on the TaC: Cu/4 H Silicon Carbide Heterostructure
###### Abstract  
Photodetectors (PDs) based on 4H silicon carbide (SiC) have garnered significant interest due to their exceptional optoelectronic properties. However, their photoresponse is typically restricted to the ultraviolet (UV) region, with limited light absorption beyond 380 nm, which constrains their utility in visible light detection applications. To overcome this limitation, an efficient photodetector was developed using an alloy with TaC (80%) and Cu (20%) on a 4H n-type SiC substrate, enabling effective light detection at 405 nm. The device exhibited high performance with a high photoresponsivity of 1.66 AW\({}^{-1}\) and a specific detectivity of \(2.69\times 10^{8}\) Jones at 405 nm. The superior performance of the device is ascribed to the enhanced electrical conductivity and optical absorption of the TaC: Cu layer on the 4H SiC substrate, particularly in the near-ultraviolet region. This photodetector combines ease of fabrication with significant performance improvements, expanding the potential applications of 4H SiC in high-temperature optoelectronics. It also introduces a promising pathway for enhancing 4H SiC-based photodetection capabilities across broader spectral ranges. 31 December 2024111 January 202  
oxide (Ga\({}_{2}\)O\({}_{3}\)) [15; 16; 17], and silicon carbide (SiC) [18; 19] have received much attention in photodetector applications. These photodetectors can efficiently absorb ultraviolet (UV) light, and they are known for their robustness, low and dark current, high-speed response, high working temperature, and lower noise levels [20; 21]. Among these wide bandgap semiconductors, SiC has garnered much interest in different areas of applications owing to its enormous electric field strength, high bond strength, and high electron saturation velocity [22; 23; 24]. Recently, it has been extensively harnessed for building ultraviolet photodetectors thanks to its advanced manufacturing technology, high thermal conductivity (3.7 W/cm\(\cdot\)K), low intrinsic carrier concentrations, and high radiation resistance [25; 26; 27; 28]. Many polytypes of SiC exist, including 3C (\(\beta\)),4H, and 6H (\(\alpha\)) [29]. Among these SiC polytypes, 4H SiC with a wide bandgap of 3.26 eV was exploited for building ultraviolet photodetectors [30]. However, these photodetectors cannot absorb or respond to light in the visible region since the cut-off wavelength of the SiC is 380 nm [2; 31]. Therefore, many materials were integrated with SiC to extend its spectral photoresponse from the ultraviolet to the near ultraviolet region and visible region. For example, [PERSON] et al. integrated 4H-SiC with transition metal dichalcogenides (TMDCs) such as (SnS\({}_{2}\)). SnS\({}_{2}\) was first fabricated on SiO\({}_{2}\) using the mechanical exfoliation method and then transferred to the SiC substrate using a dry transfer process. Even though this device showcases a high responsivity of 2.42 \(\times\) 10\({}^{4}\) A/W, the time response is still relatively high at around 17 ms. In addition, the fabrication of this device using mechanical exfoliation is restricted for research and prototypes and not suitable for large-scale applications. [PERSON] et al. fabricated a single B-doped 3C-SiC nanobelt which detects light over 380 nm [32]. The device also demonstrated excellent responsivity and was able to work well at high temperatures; however, its time response was a bit high. Recently, [PERSON] et al. integrated the tantalum boride with 6 H SiC, forming a heterojunction. This device displayed a responsivity of 2.9 A/W and a time response of 260.5 ns at 504 nm [31]. Despite having excellent reported responsibility, the thickness of this device is too high at about 540 nm, which is a bit expensive to fabricate. Therefore, a new material that can boost the spectral photoresponse of SiC with a low response time through a facile fabrication process is of great importance.