Properties of Low-Temperature GaAs Obtained by LPE Method for Terahertz Devices

The paper presents the results of studying the peculiarities of the high-resistivity low-temperature gallium arsenide formed by the liquid-phase epitaxy (LPE) method under the influence of complex doping of gallium melts with the rare earth element dysprosium and aluminum. The electrophysical properties of the epitaxial layers were studied using the Van der Pauw method. The measurements were carried out in the frequency range of 80–145 GHz using a quasi-optical setup based on a VNA vector analyzer with a pair of frequency expanders operating in the VDI WR-3.4 range. This made it possible to measure the full complex scattering parameters of the two-pole. It is shown that at concentrations of dysprosium (3.7–5.0)×10^–2 at.% and aluminum (2.1–3.8)×10^–4 at.%, high-resistivity layers of GaAs, Al_0.05Ga_0.95As, Al_0.1Ga_0.9As with resistivity values of (3–7)×10⁵ Ω⋅cm are formed. The comparison of the studied transmission-reflection spectra of terahertz signals in the specified frequency range through the epitaxial structure of GaAs–SiGaAs (substrate) and the semi-insulating gallium arsenide substrate showed that they were identical. Low-temperature LPE, which is based on the simultaneous doping of gallium melts with aluminum and dysprosium, can be used to form high-resistance layers of gallium arsenide and its solid solutions suitable for use in devices of the terahertz range.