Photoluminescence from SiO_x layers containing amorphous silicon nanoparticles

Abstract

The article summarizes the main results of a systematic study on the preparation of amorphous SiOx thin films with various contents (1.1≤ x ≤1.7) by thermal evaporation of SiO in vacuum, growth of amorphous Si nanoparticles by furnace annealing at 973 K for various times (5–200 min) and investigation of photoluminescence (PL) from the annealed films. Infrared (IR) transmission measurements prove the annealing‐induced phase separation. Raman scattering data indicate the formation of pure amorphous Si phase. Intense room‐temperature PL is detected from films with x ≥ 1.5, visible with a naked eye. Two PL bands are resolved, peaked at around 2.3 eV and in the range 1.6–2.2 eV. The former does not shift appreciably with varying annealing time and initial film composition. It is related to radiative recombination via defect states at the a‐Si/SiOx interface. The maximum of the low‐energy band shows a gradual red shift with decreasing x and increasing annealing time, i.e., with increasing nanoparticle size. This is related to carrier recombination in amorphous Si nanoparticles. Investigations of thermal quenching of the PL confirm the last assumption. Room‐temperature PL spectra of SiOx films with four different compositions annealed in an Ar atmosphere at 973 K for 60 min. The dash‐dot spectrum was measured on a film with x = 1.15 annealed for 30 min at 523 K.

Facile Synthesis of g-C3N4/TiO2/Hectorite Z-Scheme Composite and Its Visible Photocatalytic Degradation of Rhodamine B

“…Photoluminescence (PL) spectra were obtained to study the separation and recombination of photogenic e − and h + . Figure 5 shows the PL spectra and the Gaussian function fitted graphs (R 2 = 0.996) for g-C 3 N 4 , TiO 2 /hectorite and g-C 3 N 4 /TiO 2 /hectorite [ 39 ]. For g-C 3 N 4 , the emission peak at 447nm corresponds to the absorption band in UV-Vis DRS spectrum.…”

“…After fitting by Gaussian function, there are two peaks at around 464 and 525 nm, most probable corresponding to Vo with two trapped electrons (F center) and one trapped electron (F + center) [ 16 , 39 ]. Moreover, a peak appears at 574 nm, and may be assigned to the self-trapped excitons [ 43 ].…”

Solid-state reduction of silica nanoparticles via oxygen abstraction from SiO4 units by polyolefins under mechanical stressing

“…Silicon suboxides, SiO x (1 # x < 2), including nominal SiO, gather increasing interests in view of their diverse application potentials, e.g. coating materials for anti-reection, [1][2][3] photoluminescence 4,5 or anode materials for Li ion batteries. [6][7][8][9] SiO x is usually prepared via a thermal reduction of SiO 2 , 10,11 although oxidation of Si metal is also explored as a minor option.…”

Influence of swift heavy ion irradiation on the photoluminescence of Si-nanoparticles and defects in SiO2

“…Therefore, both the excess of implanted Si and the post-implantation annealing parameters, such as temperature and duration, should be optimized for the most efficient SiNP PL. It is worth noting that we use the term 'nanoparticle' instead of 'nanocrystal' in this work since both crystalline and amorphous SiNPs have been reported to show PL [17][18][19].…”