Anomalous thermal redistribution of beryllium implanted in InGaAs: a possible interaction with extended defects

Simulation of p‐type diffusion in compound semiconductor: the case of beryllium implanted in InGaAs

“…Due to "uphill" diffusion the beryllium concentration profile after annealing was characterized by two pronounced peaks. Contrary to the models considered in [1,13], the presented work here assumed that the cause of "uphill" diffusion to be the nonuniform distribution of group III self-interstitials. This nonuniform distribution was formed due to the absorption of point defects on the extended defects and on the surface of a semiconductor.…”

“…The systems of equations used in [1,13] for simulation of the redistribution of ion-implanted beryllium during rapid thermal annealing described the diffusion due to the kick-out mechanism involving interstitial beryllium only in the one specified charge state. In comparison with the equations presented in [1,13] the proposed system of Eqs. (2) and (3) simultaneously takes into account a great number of diffusing species for all possible charge states.…”

“…Fitting to the experimental data resulted in extracting the values of beryllium diffusivity and other parameters describing Be diffusion in InGaAs. However, some questions are still unresolved: for example, absorption of selfinterstitials by extended defects and absorption of interstitial beryllium atoms [1,13] or pairs "beryllium atom-self-interstitial" can equally occur. Taking into account impurity absorption the system of equations was complemented by the equation describing the conservation law for beryllium atoms incorporated with extended defects.…”

“…These two peaks indicated that pronounced "uphill" diffusion of impurity atoms occurred in two different regions. To explain "uphill" diffusion, it was supposed in [1,13] that migrating interstitial dopant atoms were bonded with extended defects produced by phosphorus implantation. Indeed, only a peak adjacent to the surface was observed after annealing of GaAs substrates implanted with beryllium [26].…”

“…It is proposed in the model presented that "uphill" diffusion occurs due to the formation of the nonuniform distribution of nonequilibrium self-interstitials, but it was suggested in [1,13] that a direct absorption of Be interstitials by extended defects had occurred. To confirm our assumption, the following calculation was carried out.…”