INFLUENCE OF THE MEYER-NELDEL RULE ON CHARGE DEEP LEVEL TRANSIENT SPECTRA

Peter Kluvánek - Drahoslav Barančok - Vojtech Nádaždy

   energy levels is investigated. We performed computer simulations of QDLTS spectra for a box-shaped energy distribution G(E) considering MNR via energy dependence of the exponential prefactor t₀ of the charge emission rate defined by t₀=t₀₀exp(-E/E₀). The main feature of these simulations is that below the critical temperature T₀=E₀/k the QDLTS spectra do not become broader with increasing the rate window as those observed for the distribution G(E) with energy independent t₀. To justify the viability of this description, we measured the continuum of interface states of two MOS structures prepared on crystalline silicon (c-Si) and undoped hydrogenated amorphous silicon (a-Si:H) substrates. Performed simulations were related to QDLTS spectra measured with large-pulse excitation which give a response from a wide energy interval. Unlike the former sample, QDLTS spectra of a-Si:H sample did not broaden with increasing the rate window. Their behaviour can be interpreted by MNR underlain in the prefactor t₀ providing support for our consideration. Using a small-signal QDLTS method, which measures a limited fraction of the interface state continuum, the dependence of t₀ on the activation energy E was constructed for both samples. It yielded the energy independent t₀ and MN energy E₀=0.38eV for interface states measured on c-Si and a-Si:H samples, respectively.

Keywords: Meyer-Neldel rule, undoped hydrogenated amorphous silicon, charge deep-level transient spectroscopy, crystalline

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