An n-doped GaAs/AlGaAs multi-layered HEIWIP based terahertz photodetector

A heterojunction interfacial workfunction internal photoemission (HEIWIP) based terahertz photodetector with 12 periods of 1.3times10¹⁸ cm^-3 Si-doped 20 nm GaAs emitter and undoped 80 nm Al_0.09Ga_0.91As barrier has been presented in this paper. Experimental results show a threshold barrier of ~4 THz (i.e. long wavelength cutoff wavelength lambda_c~70 mm) in forward bias operation and ~9 THz (lambda_c~34 mm) in the reverse bias operation. This type of discrepancy in the threshold frequency is attributed to the formation of an interface dipole between positively charged donor atoms migrated into the barrier region and negatively charged interface states.