摘要
本文采用Ｌｏｗｄｉｎ微扰原理改进计算效率的局域密度泛函（ＬＤＦ）线性Ｍｕｆｆｉｎ－ｔｉｎ轨道原子球近似（ＬＭＴＯ－ＡＳＡ）能带从头计算方法，以平均键能Ｅｍ作参考能级，计算了以闪锌矿结构氯化硼为衬底外延生长金刚石（Ｃ／ＢＮ）、以Ｃ０．５（ＢＮ）０．５合金为衬底外延生长金刚石与闪锌矿结构氯化硼（ＣＩＢＮ）、以金刚石为衬底外延生长闪锌矿结构氯化硼（Ｃ＼ＢＮ）和金刚石与氮化硼以平均晶格常数匹配生长（Ｃ－ＢＮ）等四种不同情况下，宽禁带半导体异质结Ｃ／ＢＮ的价带偏移△Ｅｖ值，结果分别为１．５０５、１．４９４、１．３８５和１．４２０ｅＶ，得到金刚石（Ｃ）和闪锌矿结构氯化硼（ＢＮ）之间，晶格失配对Ｃ／ＢＮ异质结价带偏移△Ｅｖ值的定量影响为４～６％，但不改变其独特的Ⅱ型能带排列．
Abstract Diamond (C) and boron nitride (BN) in the zinc-blend structure both are wide gap semiconductors. In this paper, an ah-initio LMTO-ASA method improved by Lowdin principle is used to calculate the valence-band offsets △Ev in heterojunction C/BN. The calculations are performed under four conditions,i. e., C and BN are matchably grown in average lattice constant (denoted by C-BN), C is strained to match the lattice constant ofbulk BN, which is the case that a thin layer of C is epitaxially deposited on BN (denoted by C/BN), C.BN are strained to match the lattice constant of C,. 5 (BN),., alloy, which is the case that the thin layers of C and BN are epitaxially deposited on C0. 5 (BN)0. 5 (denoted by C I BN) and BN is strained to match the lattice constant of bulk C, which is the case that a thin layer of BN is epitaxially deposited on C (denoted by C\BN). The calculated results are 1.420, 1.505, 1.494, and 1.358eV, respectively. The effects of mismatch on △Ev are about 4￣ 6%,but the unusal type-Ⅱ band arrangement in heterojunction C/BN is not changed.
基金
国家和福建省自然科学基金
