Growth and Electrical Properties of Free-Standing Zinc Oxide Nanomembranes

Abstract

We report the synthesis of free-standing two-dimensional semiconductor zinc oxide (ZnO) nanomembranes (NMs) using a bottom-up approach, i.e., nanomembranes grown from the faceted sidewalls of horizontally oriented ZnO nanowires (NWs). The ZnO NMs were synthesized on r-plane sapphire substrates utilizing high purity ZnO powder and graphite mixture and oxygen as source materials and argon (Ar) as carrier gas. Material characterization confirms that the horizontally oriented ZnO NWs were guided grown via a vapor–liquid–solid growth mechanism using gold as catalyst. The ZnO NMs were nucleated from the coated gold catalysts on the sidewalls of NWs. The electrical properties of the ZnO NMs were characterized based on a back-gate field effect transistor. The estimated carrier mobility of the ZnO NM is ∼150 cm2 V–1 s–1. The as-grown free-standing NMs can serve as the fundamental building blocks for a variety of applications in electronics and optoelectronics as well as sensing technologies. The unique bottom-up s...