Homoepitaxial ZnO thin films by PLD: Structural properties

Abstract

Homoepitaxial ZnO films deposited on annealed hydrothermal O‐face ZnO single crystals show superior structural quality. This is demonstrated by narrow ZnO(00.2) rocking curves with FWHM of typically 23 to 35 arcsec, and nearly dislocation‐free TEM cross sections. Nominally undoped ZnO films indicate a minor in‐plane strain of about 250 ppm and no out‐of‐plane strain. Target doping by 0.01% P2O5 or 0.5% Li3N results in pseudomorphic film growth without in‐plane strain. Increasing doping concentration of 0.1 and 1% P2O5 results in both in‐plane and out‐of‐plane strain up to 0.9% indicating relaxed films. The O‐face polarity of the homoepitaxial ZnO films is confirmed by convergent beam electron diffraction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrical transport in strained MgxZn1−xO:P thin films grown by pulsed laser deposition on ZnO(000‐1)

“…Annealing of the substrates improves their structural quality, as reported in Refs. [22,26]. No obvious differences are found in the 002 reflection after initial annealing (not shown here, see [26]) indicating that nearly no tilt of different crystallites is present.…”

“…[22,26]. No obvious differences are found in the 002 reflection after initial annealing (not shown here, see [26]) indicating that nearly no tilt of different crystallites is present. Typical FWHM of (002) rocking curves of annealed substrates were around 22-30 arcsec for good substrates, and up to 48 arcsec for a few less perfect substrates.…”

“…Annealing of the substrates results in the observation of a single narrow peak in the (101) rocking curves for some of the substrates, as also reported in Refs. [22,26], but this structural improvement cannot be achieved for every substrate. Figures 3 and 4 show exemplarily the (002), (101), and (104) RSMs obtained on films grown on a substrate consisting of different twisted crystallites, and on a structurally better substrate, respectively.…”

“…4 and 5), giving evidence of the sharp interface between substrate and film and the homogeneous film thickness, as confirmed in the TEM cross sections in Refs. [22,26].…”

Growth and structural characterization of intrinsic, acceptor, and donor doped (Mg,Zn)O epilayers via metalorganic vapor phase epitaxy on (1 0 1¯ 0) ZnO substrates

“…Astute deposition schemes [14] have been used to achieve contiguous epilayers on c-plane ZnO by MOVPE; the realization of Frank-van der Merwe growth mode has often been limited to physical deposition techniques such as pulsed laser deposition [15,16] and molecular beam epitaxy [17][18][19][20] or solution growth [21][22][23]. In addition to high surface energies on polar planes [24], the variation of adatom mobility and diffusion with different crystallographic directions [25] may facilitate the preference of Volmer-Weber growth mode on the c-plane.…”