Phosphorus diffusion and activation in fluorine co-implanted germanium after excimer laser annealing

The diffusion and the activation of phosphorus in phosphorus and fluorine co-implanted Ge after being annealed by excimer laser are investigated. The results prove that the fluorine element plays an important role in suppressing phosphorus diffusion and enhancing phosphorus activation. Moreover, the rapid thermal annealing process is utilized to evaluate and verify the role of fluorine element. During the initial annealing of co-implanted Ge, it is easier to form high bonding energy F_nV_m clusters which can stabilize the excess vacancies, resulting in the reduced vacancy-assisted diffusion of phosphorus. The maximum activation concentration of about 4.4×10²⁰ cm^-3 with a reduced diffusion length and dopant loss is achieved in co-implanted Ge that is annealed at a tailored laser fluence of 175 mJ/cm². The combination of excimer laser annealing and co-implantation technique provides a reference and guideline for high level n-type doping in Ge and is beneficial to its applications in the scaled Ge MOSFET technology and other devices.     

氧气退火温度对室温脉冲激光沉积氧化镓薄膜特性的影响

高质量氧化镓薄膜的获得是实现高性能氧化镓电子和光电子器件的重要前提条件之一。采用脉冲激光沉积技术,在室温下蓝宝石衬底上沉积氧化镓薄膜,并在氧气氛围下进行不同温度的退火,研究氧化镓薄膜特性的变化规律。结果表明：室温下沉积的氧化镓薄膜为非晶态,随着退火温度的升高,薄膜结晶程度变高,禁带宽度变大;退火前后氧化镓薄膜中都存在两种氧化价态镓,说明薄膜处于晶格氧缺失的状态;随着退火温度的升高,低价态镓比例减少,晶格氧的比例增加,薄膜质量升高;然而,过高的退火温度导致衬底中的铝扩散进入薄膜,薄膜质量变差,室温下生长的薄膜质量较差且与衬底之间的热膨胀系数和晶格失配,导致氧化镓薄膜高温退火时出现开裂的现象。