Temperature dependence of electrical properties in Be-implanted semi-insulating GaAs

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Abstract
The Hall coefficient and sheet resistivity have been measured as functions of temperature for Cr‐doped semi‐insulating GaAs implanted with 100‐keV Be ions at fluences between 1×1013 and 5×1015 cm−2. Impurity conduction influences or dominates hole transport processes at all temperatures for fluences of 1×1014, 4×1014, and 5×1015 cm−2, but is evident only for T 13 and 4×1013 cm−2. Analysis of higher‐temperature sheet‐hole concentration data for these lower‐fluence implants indicates the implanted layers are heavily doped and compensated, and the activation energy Ea decreases with increasing ionized acceptor concentration Nai. These results, along with an earlier result for a much lower concentration of implanted Be acceptors, can be represented by Ea=28.4 meV −(1.77×10−5) N1/3ai. In addition, measurement of electrical properties as a function of room‐temperature sample‐storage time indicates slow activation of compensating donors for the 4×1013‐cm−2 implant. This effect is not observed for 4×1014‐ and 5×1015‐cm−2 implants.