Semi-Insulating III–V Materials pp 183-189 | Cite as

# True Mobilities in Semi-Insulating O- and Cr-Doped GaAs

## Abstract

It is well known that an analysis of the magnetic field dependences of the resistivity *ρ* and Hall coefficient R, in nearly intrinsic material, will uniquely yield *μ* _{n}, *μ* _{p}, n, and p as long as *single* -carrier magnetic field dependences are not important. Unfortunately, recent data indicate that such effects are often important in semi-insulating GaAs and thus a new approach is necessary. We suggest an approach that requires only the usual, low field Hall effect and resistivity parameters, R_{0}, and ρ_{0}, but that also assumes knowledge of the intrinsic carrier concentration n¡, and the hole mobility *μ* _{p} as a function of the electron mobility, i.e. *μ* _{p} = f(*μ* _{n}).We describe analyses which yield n_{i}≏(2.6±0.5)×10^{6} cm^{-3}, and a *tentative* relationship for *μ* _{p} namely, *μ* _{p} ^{-1} ≏ 9×10^{-4} + 13*μ* _{n} ^{-1} . Curves of *μ* _{n} versus R_{0}/*ρ* _{0}, with *ρ* _{0} as a parameter, are calculated by using these relationships. For *ρ* _{0} ≤4×10^{6} Ω-cm, the only solutions are *μ* _{n} ≈ R_{0}/*ρ* _{0} which means that simple Hall measurements will suffice for nearly all O-doped and undoped semi-insulating GaAs. For higher *ρ* _{0}, the solutions are double-valued, and means of selecting the proper solution are discussed. A simple compensation-distribution model is presented which yields the positions of the ‘O’ and Cr energy levels.

## Keywords

Hall Coefficient Magnetic Field Dependence Conductive Sample Mixed Conduction Intrinsic Carrier Concentration## Preview

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## References

- 1.See, e.g., Putley, E.H. (1968).
*The Hall Effect and Semiconductor Physics*, ch. 3. New York; DoverGoogle Scholar - 2.
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