CHAPTER VII

        COMPARISON OF THEORETICAL AND EXPERIMENTAL RESULTS


7.1 Conductivity Mobilit~y

     Conductivity mobility was evaluated by substituting the measured resistivities into equation (4.7). Figure 7.1 shows the hole mobility plotlted as a function of hole density at 300 K for boron-doped silicon. Curve 1 represents the theoretical results of equation (3.23), and curve 2 was reproduced from the work of Wagner [8].   Our calculated values are within 6 percent of the values reported by Wagner for
         17    - 3
NA :s 3x10  cm   .For higher values of hole density our calculated values are substantially higher than those of Wagner.   As previously explained by Li [17], this discrepancy is due to Wagner's assumption of complete ionization of boron impurities. This assumption is valid only at low dopant densities or at high temperatures where full ionization of boron atoms prevails. The theoretical calculation is in

excellent agreement (within three percent) with experimental data reported by Thurber et al.[12]. This gives support to the validity of ionization calculations based on equations (4.2) through (4.6). Mobility values reported by Horn [13] are also in Yeasonable agreement with our theoretical results.  The data points shown in Figure 7.1 were corrected for deionization effects via equations (4.2) through (4.6).