Homoepitaxial Growth of ZnO by Metalorganic Vapor Phase Epitaxy

Abstract

Homoepitaxial technique of metalorganic vapor phase epitaxy (MOVPE) was used for the growth of high quality epitaxial ZnO layers. Two conditions, proper thermal treatment of substrate prior to the growth for obtaining flat surface and high flow rate ratios of source materials, nitrous oxide (N 2 O) and diethylzinc (DEZn), were found to be important. Surface roughness below 1 nm as well as strong free exciton emission at 15 K of an MOVPE-ZnO layer on a bulk ZnO substrate have demonstrated the high potential of MOVPE for ZnO.

Homoepitaxial growth of ZnO by metalorganic vapor phase epitaxy in two-dimensional growth mode

“…Despite of the straightforward advantages of homoepitaxy, i.e., perfect matching of lattice constants and thermal expansion coefficients and the expected lower dislocation densities, only a few reports on homoepitaxial growth of ZnO layers by molecular beam epitaxy (MBE) [8][9][10][11][12][13][14] or metalorganic vapor-phase epitaxy (MOVPE) [15,16] exist. The main reasons were the lack of ZnO substrates in general and an insufficient surface preparation for epitaxy.…”

“…However, in spite of thermal treatment, a pronounced tendency towards 3D growth and tensile stress in the layers was reported in MBE [10,11,14]. Also, for MOVPE a columnar growth mode was reported [15,16] resulting in a rough surface morphology preventing high-quality epilayers, which are considered to be a prerequisite for reliable and reproducible p-type doping [19].…”

InGaN growth with various InN mole fractions on m-plane ZnO substrate by metalorganic vapor phase epitaxy

“…Because there were many scratches present on the as-received ZnO substrates, surface treatment was necessary to make the substrates better suited for epitaxial growth [9]. The surface morphology of the annealed ZnO substrates was examined by AFM and the presence of the atomic step was confirmed.…”

Growth of ZnO Layers by Metal Organic Chemical Vapor Phase Epitaxy

“…It is usually grown by molecular beam epitaxy (MBE) or laser ablation techniques and only a few reports on ZnO growth by metal organic chemical vapor phase epitaxy (MOVPE) exist [1][2][3][4][5][6][7][8][9]. One problem for ZnO growth by MOVPE is the strong reactivity of the Zn and oxygen precursors leading to unwanted gas-phase reactions.…”

“…It is, for example, well known that O 2 or H 2 O as oxygen precursors strongly react with DEZn [5,10]. Less reactive gaseous precursors like N 2 O have proved to be suited for ZnO growth [5,8], but require high growth temperatures due to the poor decomposition of N 2 O at low temperatures. Organic oxygen precursors like alcohols have a tendency to be less reactive than O 2 or H 2 O [11] and show good decomposition even at low growth temperatures.…”