Epitaxial growth of high-quality ZnS films on sapphire and silicon by pulsed laser deposition

Abstract

We report, for the first time, epitaxial growth of high-quality ZnS films on sapphire and silicon substrates, using pulsed laser deposition. X-ray diffraction results show that at all growth temperatures from 200 • C to 680 • C, epitaxial wurtzite (002) ZnS films have been successfully grown on (10 12) sapphire and (001) silicon substrates. X-ray diffraction data yield full width at half maximum 2θ values of 0.13 • for as-grown samples, compared with 2θ values of 0.09 • and 0.08 • for the bare sapphire and silicon substrates respectively.

Compositional and structural properties of pulsed laser-deposited ZnS:Cr films

“…ZnS and Si has lattice mismatch of 0.40 % which is very low compared to other substrates like GaAs, GaP, Ge, and Al 2 O 3 [19]. But, due to thermal expansion difference and polarity, Si is not an ideal match with ZnS and nor are the other substrates mentioned above.…”

“…ii) Silicon is an earth abundant material like ZnS. iii) ZnS has been deposited on Si in several works and many challenges are known [19,24].…”

Pulsed laser deposition from ZnS and Cu2SnS3 multicomponent targets

“…It is therefore possible to grow films which otherwise would require a much higher substrate temperature, and which grow under strong non-equilibrium conditions. Even for compounds with volatile elements the thin films usually exhibit optical, electronic and structural properties similar to the bulk [4][5][6][7]. However, for some materials with volatile components such as oxygen or sulfur, a part of the volatile fraction may be lost during the transfer to the substrate or during the film growth [2,8], which, for example, for oxides may lead to "metallic" rather than oxide films [9].…”

“…Though some researchers have used H 2 S as background gas for PLD of ZnS [10], other groups have succeeded in using PLD with no background gas or with Ar to make chalcogenide thin films without significant S deficiency or loss of crystallinity, e.g., ZnS, AsS and GeS [5][6][7]11].…”

“…It is a stable material transparent to infrared light, and in crystalline form it displays photo-, cathode-and electroluminescence when doped, e.g., with Mn [5,11].…”