Gallium doping dependence of single-crystal n-type Zno grown by metal organic chemical vapor deposition

Ga-doped ZnO nanowire nanogenerator as self-powered/active humidity sensor with high sensitivity and fast response

“…Ga 3þ ions have smaller radius and more positive charges than Zn 2þ [11], and Ga dopant incorporating into ZnO NWs can product more shallows/native defects, such as oxygen vacancies or Zinc interstitials, leading to the high sensitivity [11,12,16]. The Ga doping concentration is not high (1.18%), thus the self-compensation mechanism can be neglected [15]. Also, Ga 3þ ions produce high local charge density and strong electrostatic field, and provide good sites for chemisorption of water molecules, leading to the fast response [11].…”

“…When the Zn atoms are substituted by Ga, the Fermi level shifts from the valence band maximum to the bottom of the conduction band, resulting in a shallow donor level at the bottom of the conduction band [13,14]. It has also been reported that at high doping concentration (>3.8%), the self-compensation mechanism can cause acceptor level in the conduction band, reduce carrier concentrations and decrease the conductivity [15]. At the same time, Ga 3þ ions have more positive charges than Zn 2þ [16].…”

Highly transparent conductive Ga doped ZnO films in the near-infrared wavelength range

“…The (0002) peak for Ga doped ZnO films shifted to the higher angle, indicating the decrease of lattice constant along the c-axis due to Ga incorporation. Since bond length of Ga-O (1.92 Å ) is [10,16], Ga substituted at Zn sites would reduce the lattice constant along the c-axis, which is responsible for the shift of peak (0002). From Table I, it is demonstrated that the FWHM values increase with increasing Ga contents from 0.0 to 3.6 at.%, suggesting that the incorporation of Ga into ZnO film leads to degradation of crystal quality.…”

Development on transparent conductive ZnO thin films doped with various impurity elements

“…However, the NBE transition red-shifted from 3.298 to 3.260 eV with increasing carrier concentration (caused by interstitial Ga) rather than the dopant contents [26]. Doping with Ga introduces a shallow donor energy level E Ga under the conduction band.…”