On the origin of inter band gap radiative emission in crystalline silicon

Abstract

Crystal imperfections degrade the quality of multicrystalline silicon wafers by introducing alternative recombination mechanisms. Here we use non-destructive hyperspectral imaging to detect photoluminescence signals from radiatively active recombination processes over the wafer with a highly resolved spectral third dimension. We demonstrate that band-to-band recombination can be visually separated from recombination through traps across the whole surface of a wafer using hyperspectral imaging. Our samples are studied in the near infrared wavelength region, 900-1700 nm, which includes the region of the so called D-band emission lines. These constitute four resolved emission lines found in the photoluminescence spectrum of silicon, commonly related to recombination through shallow inter-band gap energy levels near the conduction- and valence band edges. The shape and structure of these emissions from our measurements suggest that all the D-lines have different origins

Micrometer-Scale Deep-Level Spectral Photoluminescence From Dislocations in Multicrystalline Silicon

“…Sekiguchi et al [21] found the varying intensity ratio of D3/D4 along the slip lines of dislocations, and suggested that D3 is not the phonon replica of D4. Recently, employing a hyperspectral PL imaging technique at 110 K, Burud et al [22] had the same findings in mcSi wafers, and proposed that D3 and D4 could have different origins.…”

“…Others reported spectra with the D2 line present, but with D1 absent [9], [13]. Some pointed out a large change in the D1/D2 intensity ratio depending on the locations in the wafers [8], [21], [22], inconsistent thermal behaviors between D1 and D2 [8], or the difference in mapping images of D1 compared with other D lines [15]. Therefore, some uncertainty remains regarding the connection between D1 and D2.…”

Defect related radiative recombination in mono-like crystalline silicon wafers

“…In this work, we utilise a spectrally resolved photoluminescence (SPL) method of cooled mono‐like wafers, to study the distribution of these mechanisms in the bottom, middle and top of a pilot‐scale mono‐like silicon ingot. This method has previously been employed with success for multicrystalline material . The purpose is to study the lateral and spectral distribution of these mechanisms in order to gain fundamental insight into the distribution of impurities – possibly in combination with dislocations.…”

Distribution of radiative crystal imperfections through a silicon ingot

“…Recently Mchedlidze associates screw dislocations with a small twist angle to the D-lines and the edge dislocations to non radiative recombination. 13 Investigation of DRL is mainly performed by laboratory-based spectroscopic point mapping methods, such as described by Mudryi et al 14 and Ostapenkoet al 8 Recently single band methods using band pass filters on InGaAs cameras have been reported by Mankovics et al 15 and Schmid et al 16 Also hyperspectral technologies have been applied by Peloso et al, 17 as well as by Olsen&Flo 18 and Burud et al 19 The advantage of using hyperspectral imaging is that the entire spectrum is acquired at each point. Instead of selecting a priori regions for detailed studies with e.g.…”