The first systematic analysis is made of the phenomenological theory and experimental results on nonequilibrium chemoeffects which are the result of excitation of the electron subsystem of a crystal by the energy evolved in the course of a heterogeneous chemical reaction. These effects are analogs of such classical optical phenomena as the photoconductivity or the photovoltaic and photomagnetoelectric effects (nonequilibrium chemoconductivity, chemovoltaic and chemomagnetoelectric effects). The nonequilibrium chemoconductivity DELTA sigma * was detected experimentally for CdS and intrinsic Ge as a result of excitation by atomic hydrogen. The mechanisms responsible for the nonequilibrium conductivity were quite different in these two cases: the charged form of chemisorption was involved in the case of CdS and the neutral form in the case of Ge. The chemoexcitation cross section was calculated for CdS and found to be OMEGA equals (5 plus or minus 1) multiplied by 10** minus **1**7 cm**2 at T equals 300 degree K. The chemomagnetoelectric effect was investigated for intrinsic Ge excited with H atoms. The chemomagnetic emf V//c//h//m was 6. 25 multiplied by 10** minus **5 V for hydrogen atom concentration n//H equals 5 multiplied by 10**1**3 cm** minus **3, total pressure 0. 5 Torr, temperature of the crystal T equals 300 degree K, and magnetic induction B equals 3. 6 multiplied by 10** minus **2 T. The values of V//c//h//m and DELTA sigma * were used to calculate the effective surface recombination velocity S//1 equals 1200 cm/sec and the rate of generation of carriers on the surface nu //1N//1 equals 4. 5 multiplied by 10**1**5 cm** minus **2. sec** minus **1. In the investigated range of magnetic induction (B equals 0-0. 15 T) the value of V//c//h//m increased linearly with B. The kinetics of the two effects, V//c//h//m(t) and DELTA sigma (t), were studied (t is the time).
|Название основной публикации||Sov Phys Semicond|
|Состояние||Опубликовано - ноя 1977|
ASJC Scopus subject areas