Observation of low resistivity and high mobility in Ga doped ZnO thin films grown by buffer assisted pulsed laser deposition

Transparent conducting n-type ZnO:Sc – synthesis, optoelectronic properties and theoretical insight

“…The equilibrium growth conditions are reflected in the chemical potentials, m i which, when varied, can simulate the experimental partial pressures defining the conditions of n and p-type defect formation. This is done within the constraint of the calculated enthalpy of the host, as per eqn (2).…”

“…The unique properties of these indispensable materials are unusual by traditional principles; the wide band gap required for optical transparency (E g 4 3.1 eV) which separates the valence band (VB) from the conduction band (CB) leads to highly resistive semiconductor behaviour in pure stoichiometric ZnO, due to the low probability of electron excitation across this threshold. However, doping of the material offers a solution to this dilemma; extrinsic doping by artificial introduction of substitutional impurities such as Al(III) 1 or Ga(III) 2 on Zn(II) crystallographic sites results in an effective local excess of electrons at the defect sites. This produces an electron donor level close to the CB minimum (CBM), which facilitates donation of electrons into the CB to confer electrical conductivity to the material whilst the wide optical band gap is retained.…”

“…The first thing to notice is that all films show a typical hexagonal wurtzite ZnO pattern, with c-axis preferential orientation along the (002) direction. 2 There is no apparent secondary crystalline phase, however this does not rule out the presence of small amounts of amorphous Sc 2 O 3 growing at the grain boundaries. There appears in Fig.…”

“…The efficiency of dopant incorporation for the thin film fabrication was calculated to be 42 AE 6% (where 6% is the standard error), from the bulk Sc : Zn ratios for all films as obtained from EDX measurements, and the ratio of Sc and Zn precursors in the initial mixtures. It is unsurprising that the quantity of Sc going into the films is consistently lower than 'expected' from the precursor ratios, given that the Sc(OAc) 3 precursor decomposes at a higher temperature than Zn(OAc) 2 ; it ought to therefore be expected that at a given deposition temperature, the Zn precursor decomposes faster than the Sc precursor, such that the quantity of Sc being incorporated into the film is proportional, but not equivalent to, the ratio of Sc to Zn precursors in the aerosol. As such, this particular measurement is unique to this synthesis, i.e.…”

Nonlinear optical properties of zinc oxide doped bismuth thin films using Z-scan technique

“…ZnO thin films can be produced by several techniques like magnetron sputtering [10], reactive evaporation [11], pulsed laser deposition [12], sol gel technique [13] and spray pyrolysis [14]. Because of the advantages of low cost, simple processing, easy control of the film thickness and large range deposition temperatures, the spray ultrasonic is an extremely reliable technique for the deposition of thin films and is used in industry for large scale production.…”