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、擴散系數與n型發射區的磷相匹配， 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擴散源，但b在硅中的固溶度大( 1000時達到5 10 ~ ( 20 ) ，擴散系數小， b在硅中的雜質分布不易形成pn結中雜質的線性緩變分布，導致器件不能滿足高反壓的要求，隨之又出現了硼鋁涂層擴散工藝和閉管擴鎵工藝，前者會引起較大的基區偏差，雜質在硅內存在突變區域，導致放大系數分散嚴重，下降時間t _ f值較高，熱穩定性差；后者需要難度較大的真空封管技術，工藝重復性差，報廢率高，在擴散質量、生產效率諸方面均不能令人滿意。
2. It's difficult to find diffusion impurity in a sentence. 用diffusion impurity造句挺難的