High Performance Pd/4H-SiC Epitaxial Schottky Barrier Radiation Detectors for Harsh Environment Applications

Area of Science:

• Materials Science
• Semiconductor Physics
• Radiation Detection

Background:

• Refractory metals are explored for 4H-Silicon Carbide (SiC) devices.
• Palladium (Pd) has not been adequately investigated as a Schottky barrier contact for 4H-SiC radiation detectors.
• Nickel (Ni) is a conventional contact metal for 4H-SiC Schottky barrier detectors (SBDs).

Purpose of the Study:

• To demonstrate Palladium (Pd)/4H-SiC epitaxial Schottky barrier diodes (SBDs) as radiation detectors for the first time.
• To compare the performance of Pd/4H-SiC SBDs with benchmark Ni/4H-SiC SBDs, particularly in self-biased mode.
• To investigate the potential of SiC as high-efficiency self-biased radiation detectors for harsh environments.

Main Methods:

• Fabrication and characterization of Pd/4H-SiC epitaxial SBDs.
• Performance evaluation under self-biased (0 V) and optimized bias conditions.
• Deep Level Transient Spectroscopy (DLTS) to analyze trap centers in the 4H-SiC epilayer.

Main Results:

• Pd/4H-SiC SBDs demonstrated superior self-biased radiation detection compared to Ni/4H-SiC SBDs.
• High energy resolution of 1.9% (self-biased) and 0.49% (optimized bias) for 5486 keV alpha particles.
• Excellent charge collection efficiency of 76% in self-biased mode due to high built-in voltage (2.03 V) and hole diffusion length (30.8 µm).
• DLTS identified Z1/2 and EH5-like trap centers, with performance limited by Z1/2 trap charge trapping.

Conclusions:

• Pd/4H-SiC SBDs represent a significant advancement in self-biased radiation detector technology.
• The high performance of these detectors highlights the potential of SiC for self-powered sensors in demanding applications.
• These findings pave the way for self-powered sensor devices in advanced nuclear reactors and deep space missions.