Plasmon resonance response to millimeter-waves of grating-gated InGaAs/InP HEMT

Abstract

Tunable resonant absorption by plasmons in the two-dimensional electron gas (2DEG) of grating-gated HEMTs is known for a variety of semiconductor systems, giving promise of chip-scale frequency-agile THz imaging spectrometers. In this work, we present our approach to measurement of electrical response to millimeter waves from backward-wave oscillators (BWO) in the range 40-110 GHz for InP-based HEMTs. Frequency-modulation of the BWO with lock-in amplification of the source-drain current gives an output proportional to the change in absorption with frequency without contribution from non-resonant response. This is a first step in optimizing such devices for manportable or space-based spectral-sensing applications.

Millimeter-wave photoresponse due to excitation of two-dimensional plasmons in InGaAs/InP high-electron-mobility transistors

“…The d-doping, instead of a thick uniformly doped layer, was chosen to avoid anomalous free-carrier effects. 12,13 Device fabrication consisted of first etching the active layers into mesas for electrical isolation. This was followed by the patterning and deposition of electron-beam evaporated Ti/Au (500 nm/2500 nm) metal pads, subsequently rapid thermal annealed to form ohmic source and drain contacts.…”

Infra-red spectral microscopy of standing-wave resonances in single metal-dielectric-metal thin-film cavity

“…For instance, surface plasmons must certainly be part of the mode description in the dielectric under the plate, with interaction between fields of plasmons bound to one plate interacting and being loaded by charges on the opposite plate. [20][21][22][23] Ultra-thin absorbers designed for the visible show resonance redshifts with decease in dielectric thickness. 8 Besides the effect of fill factor to explain the relative weakness of the isolated square absorption, diffraction must additionally cause an apparent weakening.…”

InP- and graphene-based grating-gated transistors for tunable THz and mm-wave detection

“…The resonances and their harmonics could be adequately explained if a "virtual gate" (large electron concentration) existed 4.5 nm above the 2DEG [6][7][8]. Consequently, we have also chosen a different InP-based HEMT layer structure that avoids the such virtual gate.…”

“…Two new devices were prepared, PLS023C and PLS023A, with grating periods of 10 and 0.5 µm, for mm-wave and FTIR experiments, respectively. The layer structure is the same as the device studied in [8], which is presented in Fig. 1 together with the electron density distribution as determined by Silvaco Atlas 2-D device simulator (FEM analysis software).…”

“…To measure the latter spectrum, we have interfaced a Hyperion IR microscope to a 4K Si-bolometer, an optical cryostat, and a Bruker FTIR. For PLS023C, we will seek resonance mm-wave photoresponse using and FM BWO with lock-in detection, as described in [8]. Fig.…”