Effects of defect anisotropy

The influence of anisotropy of acceptor wavefunction upon tunnelling luminescence kinetics was treated in [104]. The conclusion was drawn that for the static tunnelling luminescence it just results in the redefinition of the (Jo parameter. However, we are interested here in the non-steady-state kinetics and shall demonstrate below that, particularly at this stage, anisotropic recombination reveals distinctive behaviour which allows us to identify it. 

Since the actual angular dependence of the a r) is rather complicated (e.g., [105]), Rogulis [106] has used the following simple approximation 

Kinetics of the tunnelling recombination depends greatly upon the defect mobility (whether a static tunnelling luminescence regime at low temperatures or the diffusion-controlled regime arising at higher temperatures when defects become mobile) and their spatial distribution. 

For the static tunnelling luminescence decay and correlated defect distribution the joint density of dissimilar defects is governed by equations (4.1.40) to (4.1.42). 

The conclusion was drawn above that for the isotropic case the exponentially falling defect distribution results in I t) oc as in equa- 

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