Direct Role of Hydrogen in the Staebler-Wronski Effect in Hydrogenated Amorphous Silicon

Abstract

We report a hydrogen-related defect that establishes the direct role of hydrogen in stabilizing the silicon dangling bonds created in the Staebler-Wronski effect in hydrogenated amorphous silicon. A specific NMR signal due to paired hydrogen atoms occurs only after optical excitation, exists at an intensity that is consistent with the density of optically induced silicon dangling bonds, and anneals at temperatures that are consistent with the annealing of the optically induced silicon dangling bonds. At this defect the hydrogen atoms are 2.3+/-0.2 A apart.

Innovative Characterization of Amorphous and Thin-Film Silicon for Improved Module Performance: 1 February 2005 - 31 July 2008

“…We have previously reported an 1 H NMR signal in a-Si:H that occurs only after light soaking for 600 hours [1]. This signal, which is attributed to a pair of hydrogen atoms, exhibits similar annealing kinetics to that of the defects created during light-soaking, and the concentration of these sites is comparable to that of the defects measured by electron spin resonance (ESR).…”

“…The distance between the two hydrogen atoms in the pair is about 2.3 Å. Preliminary data on the temperature dependence of the lineshape suggested that the pair may undergo some form of local motion as the temperature increases [1], but the evidence was not compelling. In addition, our earlier measurements could not exclude the possibility that the additional lineshape was due to a hydrogen triplet with the central peak masked by the narrow line from bonded hydrogen.…”

“…In addition, our earlier measurements could not exclude the possibility that the additional lineshape was due to a hydrogen triplet with the central peak masked by the narrow line from bonded hydrogen. We have recently investigated the lineshape of this 1 H NMR feature in further detail as well as its temperature dependence at a magnetic field, B 0 , of 3.5 T.…”

Network structure and dynamics of hydrogenated amorphous silicon

“…These have been extensively discussed elsewhere [17] [18]. In this section, we mention only the case of dihydrides, both because they are important in some theories of the SWE, and also because we find that they emerge naturally in our simulations of a-Si:H. Taylor and coworkers [19] have used proton NMR to measure the distribution of proton separations in various samples of a-Si:H. Early work suggested the importance of 2.4Å [19] as a preferred proton-proton separation; more recent work emphasizes distances closer to 1.8Å [20]. The latter work has caused us to consider additional dihydrides (see Fig.…”

Color-Selective CMOS Photodiodes Based on Junction Structures and Process Recipes

“…Since a-Si:H provides advantages of high photosensitivity in a visible light region and low-cost fabrication, it is extensively employed in the bias-controlled photosensing devices [3]- [10]. However, a-Si:H suffers from the Staebler-Wronski effect which results in light-induced instability, and it is not suited to the application of circuit implementation [11]. To overcome this drawback, some researchers proposed the technology of the Thin Film on ASIC (TFA) to combine a-Si:H and crystalline silicon, which are utilized in photo-sensing and electric devices, respectively [12], [13].…”