Optimization and temperature dependence characteristics of low temperature In0.3Ga0.7As and In0.53Ga0.47As-In0.52Al0.48As semiconductor terahertz photoconductors

Abstract

Recently, detailed characterisation of materials and evaluation of devices based on low temperature (LT) grown InGaAs-InAlAs and GaAs-based terahertz (THZ) photoconductors using the Molecular Beam Epitaxy (MBE) technique have been reported by our group. In this work, the characterisation is extended in order to study the growth reproducibility of the photoconductors and the temperature dependence of their transport properties. We show that the structural, optical and transport characteristics of a photoconductor can be optimised by growing the same structure under the same growing conditions but in different MBE systems. The Hall Effect measurements over the temperature range of 100 K–400 K revealed temperature independency of the mobility within a wide range, in which the concentration is changing with the temperature. The majority of carriers are found to be electrons even in the case of Be doped samples, which is attributed to the large density of excess As anti-site atoms. The transport properties of low temperature grown materials are presented for the first time and the behaviour is found to be different to those of conventional materials, which are grown under normal growth conditions

Optimised THz photoconductive devices based on low‐temperature grown III–V compound semiconductors incorporating distributed Bragg reflectors

“…Sample D was fabricated into a dipole antenna for both emission and detection and the emitter was bias at 3V. The LT-InGaAs-InAlAs MQWs sample had already been evaluated and reported in [15,19]. The photoconductive switching speed of sample D was not as fast as reported in our previous report and the bandwidth was also narrower.…”

“…This post growth annealing was performed using a Rapid Thermal Annealer (RTA) in a nitrogen atmosphere. RTA allowed the formation of precipitates form the excess arsenic incorporated as point defects [19]. To investigate the effect of the DBR layers, materials were fabricated as antennas in the same epitaxial structures (aperture for emitters and dipole for emitters or detectors).…”

“…The materials used in the photoconductive emitters and detectors are similar to those reported previously for photo‐excited THz photoconductors [18, 19]. All materials used in this study were grown in a RIBER V100 system using the low‐temperature MBE growth technique.…”

Si‐Doping of Low‐Temperature‐Grown GaAs Heterostructures on (100) and (111)A GaAs Substrates

“…III-V semiconductors, such as GaAs, InGaAs, and InAlAs, grown by molecular beam epitaxy (MBE) at low temperatures have been proven appropriate materials for photoconductive switches, which can effectively emit and detect terahertz radiation. [1][2][3] To date the most widely used material for photoconductive devices is low-temperature-grown (LTG)-GaAs. [4,5] The material exhibits ultrafast trapping times (<1 ps) at optimized growth conditions.…”

Электрофизические и фотолюминесцентные исследования сверхрешeток \LT-GaAs/GaAs : Si\, выращенных методом молекулярно-лучевой эпитаксии на подложках GaAs с ориентацией (100) и (111)А

“…Полупроводниковые структуры на основе соединений A III B V , выращенные методом молекулярно-лучевой эпитаксии (МЛЭ) в низкотемпературном режиме (low temperature growth, LT), широко применяются для изготовления фотопроводящих антенн -источников и детекторов электромагнитного излучения терагерцевого диапазона частот [1][2][3][4]. Одним из первых таких материалов был LT-GaAs и структуры на его основе.…”