n-Type GaAs/AlGaAs heterostructure detector with a 3.2 THz threshold frequency

Area of Science:

• Solid-state physics
• Optoelectronics
• Terahertz technology

Background:

• Terahertz (THz) detection via free-carrier absorption necessitates a low internal work function (few meV).
• Previous THz detectors faced limitations in sensitivity and operational frequency range.

Purpose of the Study:

• To demonstrate a THz detector with a low work function threshold.
• To characterize the performance of a novel Si-doped GaAs/AlGaAs heterostructure for THz detection.

Main Methods:

• Fabrication of a heterostructure using a Si-doped GaAs emitter and an undoped Al(0.04)Ga(0.96)As barrier.
• Measurement of detector performance including threshold frequency, responsivity, detectivity, and quantum efficiency at cryogenic temperatures (6 K).

Main Results:

• A threshold frequency of 3.2 THz (93 µm) was achieved, corresponding to a work function of approximately 13 meV.
• Peak responsivity of 6.5 A/W, detectivity of 5.5 x 10^8 Jones, and quantum efficiency of 19% were recorded at 7.1 THz.
• The detector exhibited a broad spectral response from 3.2 to 30 THz under a bias field of 0.7 kV/cm.

Conclusions:

• The developed Si-doped GaAs/AlGaAs heterostructure effectively enables THz detection via free-carrier absorption at a low threshold frequency.
• The device shows promising performance metrics for THz sensing applications within a wide spectral range.