CAJ | 학술논문

采用基于密度泛函理论的第一性原理方法（DMOL3程序），在广义梯度近似（GGA）下，计算了硅纳米晶（Si75 H76）在B和P掺杂和乙基（-C H2 C H3）、异丙基（-C H （C H3）2）表面改性等情形下态密度、结合能及能隙的变化。结果表明：掺杂对体系的禁带宽度（约3.12 eV ）几乎没有影响，但会引入带隙态；三配位的B掺杂，在禁带中靠近导带约0.8 eV位置引入带隙态，三配位的P掺杂在禁带中靠近价带0.2 eV位置引入带隙态；四配位的B掺杂，在禁带中靠近价带约0.4 eV位置引入带隙态，四配位的P掺杂在禁带中靠近导带约1.1 eV位置引入带隙态；且同等掺杂四配位时体系能量要低于三配位；适当的乙基或异丙基表面覆盖可以降低体系的总能量，且表面覆盖程度越高体系能量越低，但在表面嫁接有机基团过多将导致过高位阻，计算时系统不能收敛。
채용기우밀도범함이론적제일성원리방법（DMOL3정서），재엄의제도근사（GGA）하，계산료규납미정（Si75 H76）재B화P참잡화을기（-C H2 C H3）、이병기（-C H （C H3）2）표면개성등정형하태밀도、결합능급능극적변화。결과표명：참잡대체계적금대관도（약3.12 eV ）궤호몰유영향，단회인입대극태；삼배위적B참잡，재금대중고근도대약0.8 eV위치인입대극태，삼배위적P참잡재금대중고근개대0.2 eV위치인입대극태；사배위적B참잡，재금대중고근개대약0.4 eV위치인입대극태，사배위적P참잡재금대중고근도대약1.1 eV위치인입대극태；차동등참잡사배위시체계능량요저우삼배위；괄당적을기혹이병기표면복개가이강저체계적총능량，차표면복개정도월고체계능량월저，단재표면가접유궤기단과다장도치과고위조，계산시계통불능수렴。
Using the first-principles method based on density functional theory ,at the generalized gradient ap-proximation (GGA ) ,the state density ,the change of binding energy and the energy gap of the silicon nano-crystals (Si75 H76 ) with the circumstances of boron (B)-doped ,phosphorus (P)-doped and the surface modifi-cation with ethyl (CH2CH3 ) ,isopropyl (-CH(CH3 )2 ) have been calculated .The results showed that the B or P-doped have little impact on the energy gap value (3.12 eV) of silicon nanocrystals (SiNcs) ,except that some energy levels will be introduced in the forbidden band .The energy level caused by three-coordinated B-doped SiNcs is Ec -0.8 eV ,while it is Ev +0.2 eV for the three-coordinated P-doped .However ,the energy level position is Ev +0.4 eV for the four-coordinated B-doped SiNcs ,and Ec -1.1 eV for the four-coordinated P-doped .Total energy of the system with the four-coordinated doped is lower than that with the three-coordi-nated doped in the other same conditions .The total energy of SiNcs system lessen when the surface is modified with appropriate ethyl or isopropyl .The total energy decreases with the surface coverage of organo-functional group increasing .But ,the calculation can’t converge because of too high resistance when the SiNcs surface are grafted with too many organic groups .