Giant Piezoresistive On/Off Ratios in Rare-Earth Chalcogenide Thin Films Enabling Nanomechanical Switching

Sophisticated microelectromechanical systems for device and sensor applicaticns have flourished in the past decade. These devices exploit piezoelectric, capacitive, and piezoresistive effects, and coupling between them. However, high-performance piezoresiitivity (as defined by on/off ratio) has primarily been observei in macroscopic single crystals.' In 10 this Letter, we show for the first time that rare-earth monochalcogenides in thin film form can modulate a current by more than 1000 times clue to a pressure-induced insulator to metal transition. Furtherniorc, films as thin as 8 nm show a piezoresistive response. The conlbination of high performance and scalability make these promising applications, such as the recently proposed piezoelectronic transistor (PET) 2,3 The PET would mechanically couple a piezoelectric thin film with II a piezoresistive switching layer, potentially scaling to higher speeds and lower powers than today's complementary metal oxide scmiconductor technology.