planar diffusion 中文意思是什麼
planar diffusion
解釋
平面擴散-
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，由於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在硅中的雜質分佈不易形成pn結中雜質的線性緩變分佈，導致器件不能滿足高反壓的要求，隨之又出現了硼鋁塗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；後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。 -
Formalin - fixed small animal brains magnetic susceptibility artifact control in single shot echo planar diffusion tensor imaging
固定小動物腦標本單次激發回波平面擴散張量成像中磁化率偽影的控制
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