Effect of Ge-Nanoislands on the Low-Frequency Noise in Si/SiO_x/Ge Structures

Abstract

Low-frequency noise of the structures with Ge-nanoclusters of rather high surface density grown on the oxidized silicon surface is investigated for the first time. It was revealed that the 1/f γ noise, where γ is close to unity, is the typical noise component. Nevertheless, the 1/f γ noise sources were found to be distributed nonuniformly upon the oxidized silicon structure with Ge-nanoclusters. The noise features revealed were analyzed in the framework of widely used noise models. However, the models used appeared to be unsuitable to explain the noise behavior of the structures studied. The physical processes that should be allowed for to develop the appropriate noise model are discussed.

Relaxation of photovoltage in ITO-Ge-Si heterojunction with Ge nanostructured thin films

“…Under high temperatures, T > 220 K, the recombination rate is determined by times of electron capture/release from traps. When temperature becomes lower, the Ge NCs becomes a giant trap for holes accumulating a positive charge causing downward band banding in the underlying Si [4,5]. On the basis of the foregoing, we assume that holes trapped by Ge are practically immobile.…”

Hopping conduction and LF noise in structures with Ge nanoclusters grown on oxidized Si(001)

“…It points to the fact that 1/f c noise sources are distributed non-uniformly over the Si/SiO x structure with Ge nanoclusters, which indicates to strong effect of surface traps on noise value. It should be reminded that the latter was not observed for the reference structures for which homogeneous distribution of 1/ f c noise sources appears to be typical [21].…”

“…Previously, we showed [21] that the noise spectra of the structures studied are of the 1/f c type in the low-frequency range, where c is about unity, and appear to be significantly higher than in the case of reference Si/SiO x structures without Ge nanoclusters at room temperature. At high enough frequencies, the Nyquist noise of structure resistance dominates the noise spectra measured.…”

“…The latter significantly exceed typical values of a H presented elsewhere [22]. At the same time, when analyzing the 1/f noise in the framework of McWhorter model [23], ascribing it to fluctuations of a number of free charge carriers which accompany their capture/emission on traps located in the oxide covering the semiconductor, extremely high values of trap concentration (8 9 10 16 -10 18 ) cm -2 eV -1 were found [21]. The latter points to the fact that the approaches used are not suitable in this case.…”

Physical Insights on Charge Transport Mechanism and the LF Noise Behavior in Oxidized Si Structures with Ge Nanoclusters

“…Other interesting findings concern the low-frequency noise behavior of the Si/SiO x structures with Ge-NCs. It was revealed [9] that the noise spectra of these structures are usually dominated by the 1/f component, which is lost in the frequency-independent (white) noise at sufficiently high frequencies. At frequencies f ≤ 10 Hz some Lorentzian components entered the noise spectra.…”