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Fig.2.10. A degree of stress 
relaxation in Si/SiGe/Si structures 
depending on ion energy and the 
concentrations of Ge in solid 
soutions of SiGe 
 
 
 
121 

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2.5. Thermovoltaic features of silicon film 
p-n
 structures produced by ion
-
stimulated vacuum deposition 
The ion
-stimulated methods were used to create silicon structures allowing 
conversion of thermal energy into electric one. Direct conversion of solar energy 
and heat of heated bodies, beginning from 
geothermal 
sources, 
waste gases of 
thermal electric power stations and metallurgical productions is an actual and 
topical engineering proble
m. We have proposed and justified an idea of 
thermovoltaic conversion, i.e. creation of thermal energy converters (TEC) with 
the use of polycrystalline silicon. One of the most important conditions of TEC 
operation is introducing impurities with deep energy levels of 
≥10
18
cm
-3 
into such 
silicon. 
The thermovoltaic effect was experimentally tested for the film silicon 
p-n
structures produced under conditions minimizing the effect of doping impurities. 
The TEC structures were produced with the setup of ion
-stimulated vacuum 
deposition. The films were deposited on the substrates by evaporation of a working 
material with its heating by an electron beam. The
film 
Si
structures with the 
p-n
transition 
were formed by evaporation of monocrystalline silicon of quality
KDB-
0.4 or KEF
-
20 onto the surface of substrates of KEF
-
20 (111) and KDB
-
40 (100), 
respectively. The substrate temperature was varied within the range 950
-1100K. A 
mode of deposition with the high rates ~1mkm/min was realized. The time of film 
deposition was from 1 to 5 min for different modes. 
The thermovoltaic effect was studied in the samples under conditions of 
uniform heating and subsequent smooth deposition of the whole system within the 
temperature range 300-
900K with no temperature gradient. The c
haracteristic 
temperature dependences of dark voltage and current are presented in Fig. 2.
11.