TY - JOUR
T1 - Electronic origin of the conductivity imbalance between covalent and ionic amorphous semiconductors
AU - Deng, Hui Xiong
AU - Wei, Su Huai
AU - Li, Shu Shen
AU - Li, Jingbo
AU - Walsh, Aron
PY - 2013/3/21
Y1 - 2013/3/21
N2 - Amorphous semiconductors are known to give rise to greatly reduced conductivity relative to their crystalline counterparts, which makes the recent development of amorphous oxide semiconductors with high electron mobility unexpected. Using first-principles molecular dynamics and electronic structure simulations, we have analyzed the electronic and optical properties of covalent and ionic oxide amorphous semiconductors. We observe that in covalent systems, amorphization introduces deep defect states inside the gap, resulting in a substantial deterioration of electrical conductivity. In contrast, in ionic systems, such as the transparent conducting oxide ZnO, amorphization does not create deep carrier-recombination centers, so the oxides still exhibit good conductivity and visible transparency relative to the crystalline phases. The origin of the conductivity imbalance between covalent and ionic amorphous semiconductors can be explained using a band coupling mechanism.
AB - Amorphous semiconductors are known to give rise to greatly reduced conductivity relative to their crystalline counterparts, which makes the recent development of amorphous oxide semiconductors with high electron mobility unexpected. Using first-principles molecular dynamics and electronic structure simulations, we have analyzed the electronic and optical properties of covalent and ionic oxide amorphous semiconductors. We observe that in covalent systems, amorphization introduces deep defect states inside the gap, resulting in a substantial deterioration of electrical conductivity. In contrast, in ionic systems, such as the transparent conducting oxide ZnO, amorphization does not create deep carrier-recombination centers, so the oxides still exhibit good conductivity and visible transparency relative to the crystalline phases. The origin of the conductivity imbalance between covalent and ionic amorphous semiconductors can be explained using a band coupling mechanism.
UR - http://www.scopus.com/inward/record.url?scp=84875717286&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.87.125203
DO - 10.1103/PhysRevB.87.125203
M3 - Article
AN - SCOPUS:84875717286
SN - 1098-0121
VL - 87
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 12
M1 - 125203
ER -