EFFECT OF MOBILITY GRADIENT IN INHOMOGENEOUSLY DOPED SEMICONDUCTORS

Based on a theoretically predicated impurity distribution, it has been shown that the lower minority carrier lifetime in a diffused semiconductor as compared to that measured in a uniform bulk semiconductor was solely due to the effect of electrostatic field gradient. In fact, the true impurity distribution in a diffused region has never been determined. Investigation of the effects of mobility gradient in the diffused region with assumed impurity distribution of a complementary error and an exponential function has been performed. The results showed that (1) the effect of mobility gradient contributes to the effective minority carrier lifetime with an equivalent lifetime of the order of 10 -10 to 10-12 sec, and (2) the lower minority carrier lifetime in the diffused region may be explained more commonly in terms of the effect of mobility gradient than that of the electrostatic field gradient. © 1968 The American Institute of Physics.