The relative current change, concentration, and carrier mobility in silicon samples doped nickel and at pulse hydrostatic pressure

2. Experimental section 
 
In this paper we consider the change in the concentration and mobility of charge carriers in silicon samples with 
deep levels under pulsed hydrostatic pressure. Pulsed hydrostatic pressure is a sharp increasing in the hydrostatic 
pressure of the liquid due to a sharp decreasing in its volume. As well as the contribution of thermal and vibrational-
relaxation effects in the pulse hydrostatic pressure (PHP). 
For our experiments we made silicon samples with Ni alloy with a resistivity ~ 10
3
ohm cm and with different 
types of conductivity. Doping of silicon single crystals with nickel impurities was made from a layer of Diffuser 
deposited on the silicon surface by vacuum spraying on a VUP-5 unit. Nickel diffusion was carried out in a 
horizontal SOUL-4 furnace in the temperature range T = 900÷1200 
o
С within two hours. As a Diffuser, Ni was used 
with a purity of 99.999%. After diffusion annealing, in order to remove the near-surface layer, 50-60 μm each was 
ground on each side of the samples. 
The electrical parameters of the samples (electrical conductivity, concentration and mobility of the current 
carriers) were determined by the Hall Effect of measurements [3]. 
For measuring the resistivity of the samples was used four-probe method [3]. 
2.1 Results and discussion 
 
As shown by the experimental results, the nature of the change in the concentration of current carriers in samples 
of silicon with deep levels coincides with the nature of the change in the current of these samples at a pulsed 
hydrostatic pressure. Fig. 1 shows the relative changes in current (1, 1 ‘) concentrations (2, 2’) and the mobility (3) 
of charge carriers in the highly compensated n-Si (a) and overcompensated p-Si (b) samples with 
resistivity of ~ 10
3
ohmcm. 
It is evident that under the influence of pulse pressure, carrier density, increasing, reaching a maximum value, 
further reduced and is not changed, equal to its static value Figure 1. In this variation of the current flowing through 
the sample n-Si relative changes are 65 percent. The change in the current flowing through the sample at a 
pulsed hydrostatic pressure occurs due to a change in the concentration and mobility of the current carriers. We also 
investigated contributions of changes in the concentration and mobility of charge carriers in the overall change in 
the flowing current through the sample. As shown by the results of experiments, the current flowing through the 
sample changes relative to the original value by 55 percent due to a change in concentration and by 10 percent due 
to mobility of the charge carriers. 
In the samples (p–Si ), concentration increases as in the case of n–Si , but the change in concentration 
of greater than n–Si samples. Apparently, this is due to the fact that in the p-Si  samples, the acceptor 
levels are closer to the valence band than to the conduction band. At pulse pressure, additional transitions from the 

---

444 
O.O. Mamatkarimov et al. / Materials Today: Proceedings 17 (2019) 442–445 
valence band to the deep levels of nickel occur in the samples of p-Si . And the mobility of charge carriers in 
p–Si samples, in contrast to mobility of highly compensated n–Si samples on the contrary decreased (8–
10%) at IHP.
Fig. 1 The relative changes in current (1, 1’) the concentration (2, 2’) and the 
mobility (3)
of charge carriers in the samples 
n-Si and p-Si 
with resistivity’s ~ 10
3
ohmcm at a hydrostatic pressure pulse amplitude P = 510
8
Pa. dP/dt = 210
8
Pa/s. 
To study the mechanism of manifestation strain effect in Si  samples were tested relative concentration and 
current change when the temperature changes by an electrical heater (1a, b the curves 1’, 2’). In this case the test 
samples were directly under the influence of hydrostatic pressure. As can be seen from the figures the temperature 
of the changes in the concentration of 50% of the dynamic concentration changes. According to our assumption of 
the remaining 50% accounted for by changes in the vibrational-relaxation effects stimulated pulse hydrostatic 
pressure. It also shows that both the n- Si samples as well as in the static part of the changes in the 
concentration p-Si  samples is approximately equal to the amount of 40% of the total change.