Ge+ Dose Dependence of Electrical Characteristics in Germanium Ion-implanted Polycrystalline Silicon Films

The dose dependence of electrical characteristics in germanium ion (Ge⁺)-implanted polycrystalline silicon(poly-Si) films amorphized by Ge⁺ implantation and subsequently solid-phase-recrystallized with a low temperature annealing was investigated. It was found that the resistors and pn-diodes fabricated in Ge⁺-implanted poly-Si films have lower resistivity and higher on/off current ratio compared to those fabricated in as-deposited poly-Si films and Si⁺-implanted ones, respectively. Improved electrical characteristics for the Ge⁺-implanted n-channel TFTs, such as the high field effect mobility and the low interface trap density, were obtained when good crystallinity was achieved through implantation dose optimization. Also, the electrical characteristics of these devices were found to improve with plasma hydrogenantion.