Dopant Migration-Induced Interface Dipole Effect in n-Doped GaAs/AlGaAs Terahertz Detectors

Abstract

Abstract-A heterojunction interfacial workfunction internal photoemission (HEIWIP) terahertz detector with ∼1×1018 cm −3 n-type doped GaAs emitters in a multilayer GaAs/Al 0.13 Ga 0.87 As heterostructure is presented. The detection mechanism is based on free carrier absorption with a broad response extending to ∼5.26 THz (57 μm), corresponding to an effective workfunction of ∼21.8 meV, which is much smaller than the offset expected for an Al fraction of x = 0.13 at a 1 × 10 18 cm −3 doping. This is attributed to a reduction of the conduction band offset by interface dipole formation between the accumulated negative charges at the interface states and migrated positively charged donors in the barrier. The device has a peak responsivity of 0.32 A/W at ∼26 μm at 5 K. It is demonstrated that the dopant migration-induced interface dipole effect can be used to extend the zero response threshold frequency (f 0 ) of n-type HEIWIP detectors.

Defect-Rich Dopant-Free ZrO2 Nanostructures with Superior Dilute Ferromagnetic Semiconductor Properties

“…While the resulting systems may have collective magnetic property, the magnetism is often not uniform over the entire materials due to dopant inhomogeneity. More importantly, the dopants in a multilayer device structure have been found to migrate from the host layer to the adjacent layers during operation of the device . The elusive nature of dopants has therefore made practical implementation difficult.…”

“…More importantly, the dopants in a multilayer device structure have been found to migrate from the host layer to the adjacent layers during operation of the device. 10 The elusive nature of dopants has therefore made practical implementation difficult.…”

Oxygen-deficient dopant-free Ti3O5 and Ti2O3 ferromagnetic two-dimensional nanostructures for spin-based electronic devices

“…These challenges include the low solubility limit of transition metal ion dopants, their tendency to form clusters and to occupy sites other than the cation-substitutional ones, 5 and the likelihood of dopant migration in a multilayer device structure. 6 More importantly, studies employing X-ray magnetic circular dichroism have revealed that dopants (Co, Mn, and Cr) with unpaired d electrons are in fact not the origin of ferromagnetism. Instead, it is the dopant-induced oxygen vacancy defects that contribute to ferromagnetism.…”

Effect of emitter thickness on the spectral shape of heterojunction interfacial workfunction internal photoemission detectors

“…The heterojunction interfacial-workfunction internal photoemission ͑HEIWIP͒ detector 1,2 is a specific type of device that has been developed, which consists of several highly doped emitter and undoped barrier layers placed between highly doped contacts. Recent results from n-type HEIWIP structures show sensitivities at wavelengths up to 93 m. 3,4 The basic model 5 for the response of HEIWIP detectors consists of three mechanisms; absorption, internal photoemission, and collection of the photocarriers. While significant progress has been achieved 6 in optimizing the modeling of the absorption, there are few studies on the other two factors.…”