Large and abrupt optical band gap variation in In-doped ZnO

Abstract

Optical absorption properties of n-type In-doped ZnO films were investigated by spectroscopic ellipsometry for varying carrier concentration. The fundamental optical band gap (E0) edge of the compound showed a blueshift below the carrier concentration n0=5×1019 cm−3, which can be explained in terms of the Burstein–Moss band-filling effect. An abrupt jump of the E0 edge from blue- to redshift was observed as the carrier concentration increased beyond n0. It is interpreted as due to a merging of the donor and conduction bands of the compound near n0. The redshift increases quite linearly with the carrier concentration, reaching 600 meV for n=1.2×1020 cm−3. Such linear increase is interpreted as mainly due to a band gap narrowing caused by impurity-induced potential fluctuations.

Role of defects in one-step synthesis of Cu-doped ZnO nano-coatings by electrodeposition method with enhanced magnetic and electrical properties

“…The observed blue shift could be associated with strong quantum confinement effect, surface plasmon resonance [53], poor crystallinity of the film [54], and/or a new compound based on Cu and Zn [52]. A reduction in the amount of the blue shift at higher Cu concentration is ascribed to band tailing by Cu mixed oxidation states [55]. According to BM effect, less localized electrons of the Cu impurities occupy the states below the conduction band.…”

On the Optical, Thermal, and Vibrational Properties of Nano-ZnO:Mn, A Diluted Magnetic Semiconductor

“…The impurities, introduced into the ZnO nanostructure, can modulate the local structure and cause a dramatic change of photoelectric and vibrational properties due to the quantum confinement effect [8][9][10][11]. Therefore, ZnO:Mn is studied here with an emphasis on the local defect mode.…”

Electrical and optical properties of zinc oxide layers grown by the low-temperature atomic layer deposition technique

“…Moreover, the observed band gap shrinkage is probably a result of a merging of the donor and conduction bands as the electron concentration is large enough (the so-called Mott criterion for ZnO, discussed later on). This leads to a fact that the bottom of the conduction band is shifted downwards [22,23]. Figure 3 presents the LT PL spectra collected at 16 K on the ZnO/glass layers.…”