Quantum confinement and band offsets in amorphous silicon quantum wells

Abstract

Quantum wells (QWs) are nanostructures consisting of alternating layers of a low and high band-gap semiconductor. The band gap of QWs can be tuned by changing the thickness of the low band-gap layer, due to quantum confinement effects. Although this principle is well established for crystalline materials, there is still controversy for QWs fabricated from amorphous materials: How strong are the confinement effects in amorphous QWs, where, because of the disorder, the carriers are localized to start with? We prepare an atomistic model of QWs based on a-Si:H to gain insight into this problem. The electronic structure of our atomistic QWs model is described with first-principles density functional theory, allowing us to study the confinement effects directly. We find that the quantum confinement effect is rather weak, compared to experimental results on a similar system.

Band Offsets at the Interface between Crystalline and Amorphous Silicon from First Principles

“…We note that we expect only weak quantum confinement and charge localization effects in the amorphous part, since the charge carriers in bulk a-Si:H are localized to begin with. 29 In order to circumvent the problem with quantum confinement in the c-Si part we followed a different approach. We calculated the band structure of c-Si with 2 atoms in the unit cell and obtained a band gap of 1.14 eV (HSE06).…”

Band structural and absorption characteristics of antimonene/bismuthene monolayer heterojunction calculated by first-principles

“…For example, the quantum well is a significant material with a discrete energy level. Its band gaps always decrease as the quantum well thickness increases (Jarolimek et al, 2014). This research indicates that the size of the semiconductor is crucial in adjusting the electronic properties.…”

“…As the size increases, and the band gap decreases (Wu et al, 2005;Wilcoxon et al, 1997). Researchers have used quantum confinement to adjust the band structures of semiconductor materials (Arutyunov et al, 2018;Peng et al, 2018; OPEN ACCESS EDITED BY Haichang Zhang, Qingdao University of Science and Technology, China Chang et al, 2012;Jarolimek et al, 2014). For example, the quantum well is a significant material with a discrete energy level.…”

Effects of proton irradiation on Si-nanocrystal/SiO2 multilayers: study of photoluminescence and first-principles calculations

“…Surveying broadly studied DFT hybrid functional on various silicon related materials, we confirmed that the tendency of band gap estimation by the PBE level has been in parallel to that by the hybrid functional. [40][41][42] We expect in our model study that the PBE level discussion for three relevant configurations as shown in Fig. 5 would not be far from the hybrid functional one.…”