Sensitivity of Field-Effect Transistor-Based Terahertz Detectors.

Area of Science:

• Terahertz (THz) technology
• Semiconductor device physics
• Metrology and sensor characterization

Background:

• Field-effect transistor (FET)-based detectors are crucial for terahertz (THz) sensing.
• Sensitivity metrics like responsivity and noise equivalent power are key performance indicators.
• Existing characterization methods for these sensors lack standardization, leading to inconsistent results.

Purpose of the Study:

• To provide an overview of diverse methods for determining the sensitivity of FET-based THz detectors.
• To highlight the significant impact of effective sensor area determination on reported sensitivity values.
• To propose a path towards unified scientific metrology for FET-based THz sensors.

Main Methods:

• Review and comparison of various sensitivity determination techniques for FET-based THz detectors.
• Demonstration of characterization challenges using a 2x7 detector array with integrated patch antennas at 620 GHz.
• Simulation and experimental measurement of antenna directivity and analysis of substrate radiation effects on sensor area.

Main Results:

• Discrepancies in reported sensitivity values can reach orders of magnitude due to differing effective area calculation methods.
• Experimental and simulated directivity of antennas in a 620 GHz array suggest substrate radiation modifies the effective sensor area.
• The choice of method for determining the effective sensor area critically influences the reported sensitivity of THz detectors.

Conclusions:

• Standardized methods for determining the effective area are essential for accurate and comparable sensitivity measurements of FET-based THz sensors.
• Understanding substrate wave propagation is vital for precise characterization and improved sensor design.
• This work lays the foundation for unified metrology, benefiting researchers, users, and system designers in the THz field.