Bandgap Engineering of Amorphous Hydrogenated Silicon Carbide

Abstract

A simple model to describe the fundamental absorption of amorphous hydrogenated silicon carbide thin films based on band fluctuations is presented. It provides a general equation describing both the Urbach and Tauc regions in the absorption spectrum. In principle, our model is applicable to any amorphous material and it allows the determination of the bandgap. Here we focus on the bandgap engineering of amorphous hydrogenated silicon carbide layers. Emphasis is given on the role of hydrogen dilution during the deposition process and post deposition annealing treatments. Using the conventional Urbach and Tauc equations, it was found that an increase/decrease of the Urbach energy produces a shrink/enhancement of the Tauc-gap. On the contrary, the here proposed model provides a bandgap energy which behaves independently of the Urbach energy.

Determination of the complex refractive index and optical bandgap of CH3NH3PbI3 thin films

“…This can be achieved by using a band fluctuations average, in the free electron approximation, which serves to describe the shape of disorder induced localized states and extended states in a single equation 18,19 . Here we use our approach 20,21 , modified for crystalline semiconductors with direct bandgap. It consists of using an average JDOS to calculate the electronic transition rate and is described as follows.…”

Exploring the Interrelation between Urbach Energy and Dielectric Constant in Hf-Substituted BaTiO3

“…Earlier efforts have been successfully made by researchers to understand the behavior of Urbach energy (∼electronic disorder) through suitable modelling and also to correlate it with optical band gap. − Moreover, attempts in the direction to realize the interrelation of the dielectric constant (ε r ) with the electrical, magnetic, and absorption-related properties for various materials have also been contributed by various research groups. − In this, BTO has been a popular material for study of dielectric behavior of solids. ,,, However, reports that study the correlation of Urbach energy ( E U ) with ε r are limited. In the present work, barium titanate (BTO) has been subjected to Hf incorporation at Ti-sitesBaTi 1– x Hf x O 3 (BTHO), for which optical and dielectric measurements have been performed at various compositions.…”