Competition between Direct Detection Mechanisms in Planar Bow-Tie Microwave Diodes on the Base of...

Area of Science:

• Terahertz (THz) technology
• Semiconductor device physics

Background:

• Terahertz radiation is crucial for advanced sensors, particularly those requiring room-temperature operation without external bias.
• Bow-tie microwave diodes based on Indium Gallium Arsenide (InGaAs) structures are promising candidates for these applications.
• Existing understanding of voltage generation mechanisms in these diodes remains incomplete.

Purpose of the Study:

• To conduct a detailed analysis of the voltage detection mechanisms in bow-tie diodes.
• To investigate the impact of Indium Arsenide (InAs) inserts within the Indium Gallium Arsenide (InGaAs) layer.
• To explore the influence of varying illumination and temperature conditions on diode performance.

Main Methods:

• Fabrication and characterization of selectively doped InAlAs/InGaAs bow-tie semiconductor structures.
• Analysis of voltage-power characteristics and frequency-dependent voltage sensitivity (K_a band).
• Investigation of temperature-dependent detected voltage and its relaxation dynamics.

Main Results:

• The study reveals that the detected voltage in these bow-tie diodes is not solely due to free-carrier heating.
• The presence and influence of InAs inserts were systematically studied under different environmental conditions.
• Specific dependencies on power, frequency, temperature, and illumination were observed and analyzed.

Conclusions:

• The primary mechanism for voltage generation in these bow-tie diodes under combined light and microwave radiation is identified as a photo-gradient electromotive force.
• This finding clarifies the operational principles of InAlAs/InGaAs bow-tie diodes for THz sensing applications.
• The research provides crucial insights for optimizing the design and application of these semiconductor devices.