例句與造句

1. At the initial stage of planar technique , b was employed as ideal diffusion impurity in base - region of npn si planar devices because of the match of its solid - solubility and diffusion coefficient in si with those of p in emission - region , and the good shield effect of sio2 film to b . but because of the relatively large solubility ( 5 1020 / cm3 at 1000 ) and the small diffusion coefficient , the linear slowly - changed distribution of acceptor b in pn junction can not be formed , which could not cater to the requirement of high - reversal - voltage devics . thereafter b - a1 paste - layer diffusion technology and close - tube ga - diffusion technology had been developed , while the former can lead to relatively large the base - region deviation and abruptly varied region in si , which caused severe decentralization of current amplification parameter , bad thermal stability and high tr ; the latter needed the relatively difficult pack technique , with poor repeatability , high rejection ratio , and poor diffusion quality and productio n efficiency
   在平面工藝初期，由于b在硅中的固溶度、擴(kuò)散系數(shù)與n型發(fā)射區(qū)的磷相匹配， sio _ 2對其又有良好的掩蔽作用，早被選為npn硅平面器件的理想基區(qū)擴(kuò)散源，但b在硅中的固溶度大( 1000時(shí)達(dá)到5 10 ~ ( 20 ) ，擴(kuò)散系數(shù)小， b在硅中的雜質(zhì)分布不易形成pn結(jié)中雜質(zhì)的線性緩變分布，導(dǎo)致器件不能滿足高反壓的要求，隨之又出現(xiàn)了硼鋁涂層擴(kuò)散工藝和閉管擴(kuò)鎵工藝，前者會引起較大的基區(qū)偏差，雜質(zhì)在硅內(nèi)存在突變區(qū)域，導(dǎo)致放大系數(shù)分散嚴(yán)重，下降時(shí)間t _ f值較高，熱穩(wěn)定性差；后者需要難度較大的真空封管技術(shù)，工藝重復(fù)性差，報(bào)廢率高，在擴(kuò)散質(zhì)量、生產(chǎn)效率諸方面均不能令人滿意。
2. It's difficult to find devics in a sentence. 用devics造句挺難的