Dependence of hole velocity upon electric field and hole density for p-type silicon

The hole velocities in p-type Si have been determined for fields E to 1.1 × 10⁵V/cm at 300°K for hole densities in the range 10¹⁴ – 10¹⁶/cm³. Results significantly different from Prior's (which shows a large dependence of v upon doping) have been obtained. Our specimens were p⁺pp⁺ structures made from uncompensated, low dislocation density silicon; the p⁺ regions being diffused. Current density measurements were made as a function of applied voltage using pulse techniques. The E field was oriented in the (111) crystal direction. The measured low field Hall mobility and its established relation with drift mobility were employed to obtain the low field velocities. Steady state solutions for the injected space charge and the electric fields throughout the specimen were calculated. The injected space charge density (majority carriers) is not greatly in excess of the equilibrium hole density. Several thicknesses of the p region are studied. An analysis of the current voltage data gives a curve for the high field velocity relation v(E) which is independent of the hole concentration to within 10 per cent. At E = 10⁵° V/cm, we obtain v = 8.6 × 10⁶cm/sec.     

Temperature dependence of photodegradation in amorphous hydrogenated silicon

Measurements of steady-state photoconductivity with respect to light-induced defect generation in amorphous hydrogenated silicon (a-Si: H) show that the power index of the time evolution (long-term observation) of the photodegradation is determined by the exposure temperature and the material.     

Temperature dependence of the saturation magnetization of ion-implanted YIG films

The temperature dependence of the saturation magnetization of a series of ionimplanted YIG films is presented. The films were implanted with neon ions at an energy of 450 keV; the dose ranged from 2 to 5*10¹⁴ ions/cm². The experimental data can be described by the molecular field theory showing that the ion-implanted part of the film can be approximated as consisting of two regions each having their own magnetization and Curie temperature. The values of these magnetic parameters vary as a function of dose and differ strongly from the values for pure YIG.     

Ferromagnetism dependence on hole carriers in polycrystalline silicon films co-doped with Mn and B

Polycrystalline Si_0.96Mn_0.04:B films were prepared by cosputtering deposition followed by rapid thermal annealing for crystallization. The films are ferromagnetic with Curie temperatures of about 250 K. Through the approach of microwave plasma enhanced chemical vapor deposition, the films were treated by hydrogen plasma and boron plasma. After the plasma treatments, the structural properties of the films did not change, while both the saturation magnetization and hole concentration in the films changed. The correlation between the magnetic properties and the transport properties of the Si_0.96Mn_0.04:B films suggests that free hole carriers play an important role in Si:Mn diluted magnetic semiconductors.     

Temperature dependence of hole mobility in n-type InSb upon electron bombardment

The mobility of the minority carriers, in n-InSb was investigated from the photomagnetoelectric effect as a function of temperature in the range of 12–80 K prior to and after bombardment with 1 MeV average energy beta particles. The hole mobility shows a minimum near 40 K which can be due to the h-e scattering becoming predominant in the region where other scattering mechanisms are relatively weak. After bombardment the curves have the same form but higher mobilities. This is due to a decrease of h-e scattering resulting from the decrease of the electron concentration, as determined from independent measurements.     

Temperature dependence and asymmetry of the hypersound velocity in cyanobiphenyl liquid crystals

Measurements of the hypersound velocity have been made as a function of temperature for two principal directions in cyanobiphenyl samples. Velocity asymmetry is observed in both the nematic and smectic phases. The behaviour of the velocity in the vicinity of the phase-transition temperatures is discussed.     

Temperature dependence of angles of wetting of silicon with tin-barium melts

Experimental data on polytherms of the angle of wetting of silicon surface with tin-barium melts are presented. It is found that the polytherms are linear in the temperature range between the melting point and 900 K, exhibiting a negative slope coefficient.     

Temperature dependence of the coercive force of deformed silicon iron crystals

The temperature dependence of the coercive force of deformed silicon iron (Fe-3.15 Si) crystals was studied. It was shown that the current theories relating coercive force to dislocation density do not explain changes observed in H_c. The latter were attributed to changes in the domain structure whose necessity was proved thermodynamically.     

Temperature dependence of the heat capacity and saturation magnetization of dilute reentrant ferrimagnetic spinels

Using model objects consisting of dilute reentrant spinels Li_0.5Fe_2.5−x Ga_xO₄ with x=1.0–1.2, this paper describes the temperature dependence of the magnetic contribution to the heat capacity, C _m (T), at H=0 and temperatures exceeding the freezing temperature (T _f ∼10 K) and, for T⩾4.2 K, the low-field magnetization σ _H (T) and the saturation magnetization σ _S (T), as well as the magnetization isotherms σ _T (T) in fields of up to 10 kOe. The specific features of the behavior of the overall characteristics of C _m (T) and σ _S (T) are found for the states of a frustrated ferrimagnetic that occur in the conditions considered here (H=0 and T>T _f or T⩾4.2 K and strong magnetic fields) and are discussed in connection with changes in the magnetic excitation spectrum caused by local breakdowns of collinear spin ordering and frustrations. Zh. éksp. Teor. Fiz. 113, 1339–1349 (April 1998)     

Temperature dependence of the conductivity of a silicon inversion layer at low temperatures

The temperature dependence of the conductivity of a high-mobility silicon MOSFET is reported for temperatures from 0.2 to 23 K and electron densities from 1 to 20 × 10¹¹cm⁻². The results show a strong increase in conductivity with decreasing temperature. However, this rate of increase was observed to rapidly diminish outside of a restricted range of temperature for a given density. The decreasing temperature dependence at the lower temperatures is attributed to the saturation of screening as the effects of broadening become comparable to thermal effects. The diminishing temperature dependence at the higher temperatures puts limits on the applicability of recent calculations for the conductivity.     

Temperature dependence of the spin-lattice relaxation time for quadrupole nuclei under conditions of NMR line saturation

The contributions of different mechanisms of nuclear spin-lattice relaxation are experimentally separated for ⁶⁹Ga and ⁷¹Ga nuclei in GaAs crystals (nominally pure and doped with copper and chromium), ²³Na nuclei in a nominally pure NaCl crystal, and ²⁷Al nuclei in nominally pure and lightly chromium-doped Al₂O₃ crystals in the temperature range 80–300 K. The contribution of impurities to spin-lattice relaxation is separated under the condition of additional stationary saturation of the nuclear magnetic resonance (NMR) line in magnetic and electric resonance fields. It is demonstrated that, upon suppression of the impurity mechanism of spin-lattice relaxation, the temperature dependence of the spin-lattice relaxation time T₁ for GaAs and NaCl crystals is described within the model of two-phonon Raman processes in the Debye approximation, whereas the temperature dependence of T₁ for corundum crystals deviates from the theoretical curve for relaxation due to the spin-phonon interaction.