High mobility yttrium doped cadmium oxide thin films

作者：Kelley Kyle P^*; Sachet Edward; Shelton Christopher T; Maria Jon Paul

来源：APL Materials, 2017, 5(7): 076105.

DOI：10.1063/1.4993799

Donor doped CdO thin films on c-plane sapphire are prepared by reactive co-sputtering from Cd-metal and Y-metal targets which are driven using pulsed-dc and RF power respectively. Intrinsic CdO exhibits a carrier density of 1.8 x 10(19) cm(-3) and a mobility of 330 cm(2) V-1 s(-1). By increasing the Y-flux, carrier density values can be increased smoothly and reproducibly to a maximum value of 3.3 x 1020 cm(-3). Mobility increases with Y flux, and exhibits a broad plateau between approximately 5 x 10(19) cm(-3) and 2 x 10(20) cm(-3). Higher carrier concentrations produce a sharp drop in mobility. The increase in mobility is attributed to a reduction of intrinsic donors (i.e., oxygen vacancies) with increasing carrier density while the ultimate decrease in mobility results from a combination of factors including cadmium vacancies, reduced crystal quality, and smaller crystallite sizes, all of which accompany carrier density values greater than the mid 10(20) cm(-3) range. This work demonstrates that CdO thin films can be prepared by magnetron sputtering with transport properties and crystal quality that are comparable to those grown using molecular beam epitaxy.

• 出版日期2017-7