Effects of laser wavelength and fluence on the growth of ZnO thin films by pulsed laser deposition

Abstract

Transparent, electrically conductive and c-axis oriented ZnO thin films have been grown by the pulsed laser deposition (PLD) technique on silicon and Coming glass substrates employing either a KrF excimer laser (3. = 248 nm) or a frequency-doubled Nd:YAG laser (3. = 532 rim). The crystalline structure, surface morphology, optical and electrical properties of the deposited films were found to depend not only on the substrate temperature and oxygen partial pressure, but also on the irradiation conditions. The quality of the ZnO layers grown by the shorter wavelength laser was always better than that of the layers grown by the longer wavelength, under otherwise identical deposition conditions. This behaviour was qualitatively accounted for by the results of the numerical solution of a one-dimensional heat diffusion equation which indicated a strong superheating effect of the melted target material for the case of frequency-doubled Nd:YAG laser irradiations. By optimizing the deposition conditions we have grown, employing the KrF laser, very smooth c-axis oriented ZnO films having a full-width at half-maximum value of the (002) X-ray diffraction value less than 0.16 ° and optical transmittance around 85% in the visible region of the spectrum at a substrate temperature of only 300°C.

Growth of ZnO thin films on GaAs by pulsed laser deposition

“…It has already been shown that the pulsed laser deposition (PLD) method can be used to grow highquality c-axis oriented ZnO films on Si or glass substrates at lower temperatures than most other techniques [13, 141. In this letter we show that by employing the optimised deposition conditions previously determined [14], ZnO films having a crystalline structure amongst the best reported so far by any technique can also be grown on GaAs substrates using the PLD method.…”

Piezoelectric Size Effects in a Zinc Oxide Micropillar

“…The inset in Fig. 2 shows a selected area electron diffraction where the electron beam is parallel to the [21][22][23][24][25][26][27][28][29][30] zone axis of the ZnO. The indexed diffraction pattern confirms the hexagonal structure of the ZnO thin film.…”

“…The deposition temperature is 500°C, and the thickness of Zn film is 800 nm. The use of 248 nm KrF excimer radiation for ZnO ablation was found in previous research to produce films of significantly higher quality than those grown using longer wavelength radiation [21][22][23]. Furthermore, ablation with 248-nm radiation leads to a smooth target surface after ablation [24] and, hence, all targets used here were pre-ablated prior to initial deposition, and not polished between depositions.…”

Depósito mediante ablación con láser de láminas delgadas de (Pb,La) TiO₃ y ZnO sobre (100) InP

“…No obstante, la figura 2 muestra la formaci-n de un ZnO orientado [001]ZnO||[100]InP obtenido cuando el substrato se calienta a 350-400 o C en 0.1 mbar de presi-n de ox'geno, teniendo un h ‡bito de crecimiento columnar sin orden aparente en el plano del substrato. Se observa una alta calidad cristalina para la familia de planos {00l} (FWHM=0.20 O y ω-FWHM=2.6 O para un espesor de 260 nm) comparable con la reportada para el ZnO, sobre Si (31). La rugosidad medida corresponde al 3% del espesor de la l ‡mina depositada.…”