The n-Si/p-CVD Diamond Heterojunction.

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Devices

Background:

• Wide energy gap materials are crucial for advanced applications.
• Polycrystalline diamond layers grown by Chemical Vapor Deposition (CVD) on silicon substrates offer promising properties for sensing devices.
• Controlling deposition parameters allows tailoring diamond layer crystallinity and defect structure.

Purpose of the Study:

• To investigate the electrical conduction properties of n-Si/p-CVD diamond heterojunctions.
• To identify the dominant charge transport mechanisms within these heterojunctions.
• To develop a model describing the current-voltage-temperature (I-V-T) characteristics.

Main Methods:

• Scanning Electron Microscopy (SEM) and Raman Spectroscopy for material characterization.
• Cathodoluminescence (CL) spectroscopy to identify mid-gap defects.
• Current-Voltage-Temperature (I-V-T) measurements across a broad temperature range (77-500 K).

Main Results:

• SEM and Raman spectroscopy confirmed tunable crystallinity and defect structures in CVD diamond layers.
• CL spectroscopy detected defects within the diamond's energy gap.
• I-V-T characteristics in forward bias indicated defect-mediated hopping as the primary conduction mechanism.
• Ohmic carrier flux was enhanced by charge release from the depletion layer, dependent on defect density and applied voltage.

Conclusions:

• Defect-mediated hopping is the key mechanism limiting conduction in n-Si/p-CVD diamond heterojunctions.
• A novel model accurately describes the I-V-T characteristics, including current saturation effects.
• These findings support the potential of CVD diamond for engineered sensing devices.