COMPOSITION AND OPTICAL CHARACTERISTICS OF ELECTROCHEMICALLY-SYNTHESIZED GaAs NANOCRYSTALS

Abstract

The synthesis of the GaAs nanoparticles, having sizes 7 nm to 15 nm, by a low cost electrochemical technique has been reported. The absence of any foreign impurity has been confirmed by the Proton-Induced X-rays Emission analysis. Rutherford Backscattering measurement has been performed in order to estimate the thickness of the nanoparticlegenerated thin film as a function of the electrolysis current density. The X-ray Photoelectron Spectroscopic study confirms the formation of GaAs and exhibits the binding energy shift of the core shell electrons as an implication of the nanostructure effect. Very weak infrared luminescence due to the radiative recombination of the impurity bound exciton has been detected from yttrium-doped GaAs nanocrystals, even at room temperature.

A Review on Ge Nanocrystals Embedded in SiO2 and High‐k Dielectrics

“…[81,121] Annealing is usually performed between 700 and 900 C. [81,112,114,115,117,121] The crystallization of the Ge proportion sets in at about 700 C, [117] the one of the matrix proportion at about 800 C. [115] Hence, the formation of Ge nanocrystals embedded in amorphous Al 2 O 3 is possible. [122] Annealing at 900 C or higher leads to a significant outward diffusion of Ge (usually in the form of GeO x ). [81,115,117] The Ge nanocrystals are generally in spherical shape [76,112,114,116,121] and uniformly distributed within the matrix.…”

“…[111,115] Responsible for this is often excess oxygen in the Ge-rich film. [115] Commonly, the Ge nanoparticles experience a compressive stress, [42,76,112,117,122] which increases with the size of the nanocrystals [112] and does not relax for higher annealing temperatures. [42] The local stress was related to differences between the thermal expansion coefficients of the nanocrystals and the matrix.…”

“…Ge nanocrystals in Al 2 O 3 were studied for the use in nonvolatile memory devices [111,[114][115][116]121] and PL applications. [121][122][123] Memory structures with a single charge storage layer show very large memory windows (Figure 3). Memory windows of 4.4, [111] 4.8, [116] 4.9, [121] and 6 V [114,115] are reported.…”

“…Even larger memory windows of up to 6.4 V can be formed by using five storage layers. [111] The annealing temperature with the largest memory window was 800 C. [114] The Ge nanoparticles show also a PL signal in the visible range, which was attributed either to interface defect centers [122][123][124] or nanocrystal confined carrier recombination. [121]…”