Microwave-terahertz detection by asymmetrically-necked modulation-doped GaAs/AlGaAs structures

Abstract

Asymmetrically-necked GaAs/Al0.25Ga0.75As modulation-doped structures are examined as possible active parts of the detector for operation within 10 GHz -3 THz frequency range. The estimations of the device parameters are performed for real structure planned to be used in the experiments. Calculations show that i) sensitivity of the diodes based on modulation-doped structures at liquid nitrogen temperature is significantly higher than at room temperature; ii) this trend remains over the microwave frequency range of operation; iii) narrowing of the necked-size of the device favours an essential increase in voltage sensitivity of modulation-doped structure based devices. In the case of the device with 300 nm size of the necked-part, the sensitivity could reach 4000 V/W for microwaves and 1000 V/W at 1 THz at room temperature with respect to absorbed power. At liquid nitrogen temperature the frequency dependence of voltage sensitivity at the same conditions becomes more pronounced for microwaves - it is 30 000 V/W while in terahertz frequency range the voltage sensitivity drops to the value of 240 V/W.