Optoelectronic properties of doped hydrothermal ZnO thin films

Abstract

Phone/Fax: þ8565057650Group III impurity doped ZnO thin films were deposited on MgAl 2 O 3 substrates using a simple low temperature two-step deposition method involving atomic layer deposition and hydrothermal epitaxy. Films with varying concentrations of either Al, Ga, or In were evaluated for their optoelectronic properties. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of dopants within the ZnO films. While Al and Ga-doped films showed linear incorporation rates with the addition of precursors salts in the hydrothermal growth solution, In-doped films were shown to saturate at relatively low concentrations. It was found that Ga-doped films showed the best performance in terms of electrical resistivity and optical absorbance when compared to those doped with In or Al, with a resistivity as low as 1.9 mΩ cm and an optical absorption coefficient of 441 cm À1 at 450 nm.

Polarization-enhanced InGaN/GaN-based hybrid tunnel junction contacts to GaN p–n diodes and InGaN LEDs

“…For example, because of the high resistivity of p-type GaN (p-GaN), III-nitride-based optoelectronic devices typically require a transparent current spreading electrode to operate efficiently. Transparent conductive oxides (TCOs) such as n-type Sn doped In 2 O 3 (ITO) 1) or Gadoped ZnO 2,3) are typically employed as ohmic current spreading contacts to p-GaN. They function as Esaki tunnel diodes under a reverse bias 4) by allowing electrons to tunnel between the conduction band of the TCO and the valence band in the p-GaN at the junction interface.…”