Electrical and optical characterization of AlxGa1-xAs/GaAs p-n junctions grown via liquid phase epitaxy

Abstract

The Al_xGa_1-xAs/GaAs heterostructure system is of prime importance for use in high-speed digital and electro-optic device applications. The compositional dependence of the bandgap energy of Al_xGa_1-xAs can be tailored to meet specific device requirements such as photon emission and detection. The 0.15% lattice parameter difference between GaAs and Al_xGa_1-xAs (0 ≤ x ≤ 1.0) at 300 K ensures that the density of interface states is kept to a level that would not affect device performance. These two properties of Al_xGa_1-xAs/GaAs alloy system make it one of the most technologically important semiconductors to date.
Epitaxial layers of III-V semiconductors have well-controlled carrier recombination and transport properties, usually derived from the addition of particular dopants. Among the n-type dopants, tin (Sn) is attractive for n-type doping because of its low volatility and relatively low distribution coefficient. This characteristic is crucial to minimizing dopant losses during epitaxy. Zinc (Zn), on the other hand, is preferred for doping for doping of bulk GaAs due to its high doping efficiency and uniformity. Moreover, Zn acceptors exhibit high electrical activity and show no evidence of autocompensation. In this work, therefore, Sn and Zn were used as the n- and p-type impurities respectively.
This study aimed to fabricate Al_xGa_1-xAs/GaAs p-n junctions using the liquid phase epitaxy (LPE) technique. The growth parameters of the samples were correlated with their structural, electrical and optical properties.