Investigation of the Features of the Thermovoltaic Effect in GaSb, GaAs and GaP Binary Compounds

Abstract

The thermovoltaic effect, which is the occurrence of an electromotive force (EMF) in a substance during its uniform heating, is a promising phenomenon for the development of effective converters of solar thermal energy into electrical energy. However, the problem of suitable materials and design of the thermovoltaic element remains open. Therefore, this work is devoted to the study of the thermovoltaic effect in n‑GaSb, n-GaAs, and n-GaP binary compounds. The current–voltage characteristic (I–V curve) of the structures Ni–Ag–GaSb–Ag–Ni, Ni–Ag–GaAs–Ag–Ni, Ni–Ag–Sn–GaP–Sn–Ag–Ni, Ni–Ag–Si–Ag–Ni, and Au–Ni–Ag–Au are investigated in the temperature range of 300–500 K. As the temperature increased, shifts in the I–V curves of semiconductor structures are observed towards increasing voltage and current, which indicates the appearance of EMF and current during uniform heating. At 500 K, the points of intersection of the I–V curves with the voltage axis are 10.6 mV for GaP, 6.3 mV for GaSb, 5.3 mV for GaAs, and 0.9 mV for Si, as well as with the current axis, respectively 3.8 μA cm^–2 for GaP, 480 μA cm^–2 for GaSb, 184 μA cm^–2 for GaAs, and 2.7 μA cm^–2 for Si. Uniform heating of the structures under consideration in the dark leads to the occurrence of EMF and current in them. The thermally stimulated EMF of the GaSb and GaAs compounds was almost the same (0.2 mV) and an order of magnitude lower than the EMF of the GaP compound (2.5 mV) at 428 K.