Enhancement of terahertz electromagnetic wave emission from an undoped GaAs∕n-type GaAs epitaxial layer structure

Abstract

We have investigated the emission of the terahertz electromagnetic wave from an undoped GaAs ͑200 nm͒ / n-type GaAs ͑3 m͒ epitaxial layer structure ͑i-GaAs/ n-GaAs structure͒, where the doping concentration of the n-GaAs layer is 3 ϫ 10 18 cm −3. It is found that the first-burst amplitude of terahertz wave of the i-GaAs/ n-GaAs sample is remarkably larger than that of a n-GaAs crystal, which means that the i-GaAs layer enhances the terahertz emission intensity. The first-burst amplitude of the i-GaAs/ n-GaAs sample, by tuning the pump-beam energy to the higher energy side, exceeds that of an i-InAs crystal that is known as one of the most intense terahertz emitters. We, therefore, conclude that the i-GaAs/ n-GaAs structure is useful to obtain intense terahertz emission.

Enhancement of excitonic photoluminescence in silicon-dopedn+/i-GaAs structures

“…However, the results in terahertz frequency range are quite modest. Recently new emitters [1,2] and detectors [3] on the base of n + /n and n + /i GaAs homojunctions have been proposed. Nevertheless, despite all the theoretical and experimental research done, the physics of these devices is still under consideration.…”

Enhancement of the Excitonic Photoluminescence in n+/i-GaAs by Controlling the Thickness and Impurity Concentration of the n+Layer

“…The greatest achievements have been reported in the visible and near-infrared ranges, whereas the performance in the terahertz frequency range is still considered modest. Therefore, a new generation of emitters [3,4] and detectors [5,6], based on the construction of the n + /n and n + /i (or p + /i) homojunction, have been proposed for operations in the terahertz range. Although they hold promising characteristics, these devices are still considered experimental in nature due to the underlying physics not being fully understood.…”

Terahertz Electromagnetic Waves from Semiconductor Epitaxial Layer Structures: Small Energy Phenomena with a Large Amount of Information

“…The above-mentioned epitaxial layer structure design is based on the fundamental semiconductor physics, so that the results demonstrated here contain a large amount of information on ultrafast carrier dynamics. We organize the present chapter based on our recent works (Takeuchi et al, 2008;2009;2010). In Section 2, we review the current status of terahertz-wave spectroscopy, and discuss the hidden problems.…”