Measurements of electrical conductivity o and Hall coefficient R,, have been madeas afunction of temperature in the range room temperature to 250°C and as a function of magnetic field up to 3.2 T on single crystal n-type samples of InP with carrier concentrations in the range 3.5 x 10" to 1.2 x m-). Theoretical calculations of o and R,, have been made using the method of Fletcher and Butcher and the resulting values fitted to the experimental data by using various scattering parameters as adjustable. The parameters so obtained have then been used to predict further magnetoresistance values and values of thermoelectric power and Nernst-Ettingshausen coefficient. The predicted values of magnetoresistance and thermoelectric power show good agreement with experimental values but not those of the Nernst-Ettingshausen coefficient, possibly due to experimental problems.On a effect& des mesures de la conductivite electriqueo et du coefficient Hall R,,, en fonction de la temperature dans I'intervalle allant de la temperature du laboratoire a 250°C et en fonction du champ magnetique jusqu'i 3.2 T , sur des echantillons monocristallins de type n de InP avec des concentrations de porteurs de charge se situant dans I'intervalle 3.5 x 10" a 1.2 x loZ4 m-3. On a fait des calculs theoriques d e o et R,, en utilisant la methode de Fletcher et Butcher, et I'on a adapt6 les resultats de ces calculs aux donntes experimentales en ajustant les valeurs de differents parametres de diffusion. Ces paramtttres ont Cte ensuite utilisks pour predire d'autres valeurs de la magnetoresistance, ainsi que des valeurs du pouvoir thermoelectrique et du coefficient Nernst-Ettineshausen. On a un bon accord entre les valeurs oredites et les donnees experimentales pour la magnetoresistance et le pouvoir thermoelectrique, mais pas pour le coefficient Nernst-Ettingshausen, possiblement a cause de difficultks experimentales. Can. J. Phys., 58,923 (1980) Can. J. Phys. Downloaded from www.nrcresearchpress.com by CANADIAN FREE ACCESS 2010 + BACK FILES on 11/17/14 For personal use only.

Dark capacitance measurements have been made on Au-GaAs Schottky barriers using boat-grown, oxygen-doped n-type GaAs with room-temperature carrier concentrations from 2X10 13 to 4X10 16 cm-3. The voltage and time dependence of the capacitance was analyzed using a modified version of Goodman's model for traps in depletion layers. The results yield a concentration of the dominant active trap of 1-4X 10 16 cm-a in all the crystals examined. From the variation in the time dependence of the capacitance in the range 275°-365°K, the energy for the emission of an electron from this trap is 0.90±0.02 eV. Other aspects of the capacitance data locate this trap at around 0.7 eV below the conduction band, which is the energy previously assigned. Another, faster time-dependence observed in the higher-resistivity material was investigated in the range 225°-255°K. The activation energy associated with the latter time dependence is found to be 0.7 eV. The behavior of the capacitance at high reverse bias is explained in terms of electron capture by the dominant trap as the current increases due to impact ionization.

Me;~surenientsofelcctric;~l contluctivityo and Hall coefficientRII have been ~natleaa function of temperature in the range room to 5 W C on single c~.ystnl n-type tellul-ium doped s~mples of GaAs with ca~~rierconcent~.;~tions in the range 7.9 x lo2' to 4.7 x 10?J/niZ. Theoretical calculattionsofo ontl R,, have been niuiie on a three bani1 (I' , I., X ) ~noilel usingthe method of Flctchcrand Butcher ant1 the resulting values fitted to the experimental tlata by using the tenipefitture coefficients of the band energy differences nntl va~rious deformation potentials and band coupling coefficients a ntljustatble par;tmeters. The resultsconfi~~ni the bancl ortlering proposeti hy Aspnes but give slightly different tempel-ature coefficient values. Values itre given for the deformation potentials and band coupling coefficients and in p;lrticul;r~.the deformation potential of the I' band is found to be 16.0 1 0 . 5 eV.. -..

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Thc variation of the values of Hall coefficient R and resistance e as a function of magnetic field B is analysed for the case of an n-type semiconductor with electrons in two different sets of conduction band minima. It is shown that both eo/Ae and Ro/AR should be linear functions of B P and that the parameters of the separate bands can be determined from the slope and intercept values of such graphs. The appropriate choice of experimental parameters t o ensure the required accuracy of band parameters is discussed.La variation du cocfficient dc Hall R et de la rCsist8ivitC. e en fonction du champ magnktique 13 est analystk pour un semiconductcur du type-n avec les Olcctrons dans deux types de minima de la bandc de conduction. 11 est montr6 que eo/4e, ainsi que h',/AR, doit varier lin6aircmcnt en fonetion de B-2 c t que les parametres de chaque bande peuvent &re obtcnus L partir de la pente et de l'ordonnke A l'origine de ces courbes. I& choix approprik des diffbrents paranit'tres espkrimentaux pour assurer la precision nkccssaire dans la d6termination des paramiltres de bandcs est Bgalement discotk.