CAJ | 학술논문

用X射线双晶衍射对气源分子束外延(GS-MBE)制备的锗/硅短周期超晶格(SPS)样品进行了分析．所有样品的锗层厚度固定为1．5单原子层，而硅层厚度为1．4～3．8 nm．对于硅层厚度小于2．4nm的样品来说，双晶衍射摇摆曲线中由超晶格引起的衍射峰较宽，而且看不到干涉引起的精细结构，这表明超晶格中可能存在位错及界面不平整．对硅层较厚(＞2．9 nm)的样品，摇摆曲线中超晶格引起的衍射峰很窄，而且有明显的由干涉产生的精细结构，表明此时超晶格的质量较高，界面平整．对硅层厚度为2．1～2．9 nm的样品，超晶格对应的衍射峰可以分解为两个宽度不等的子峰，但没有精细结构出现．这个区间与文献[1]报道的在荧光光谱发现的一个异常带出现区间完全相同．本实验的X射线双晶衍射测试与分析结果支持文献[1]提出的此异常带与局部应力场引起的外延层呈波浪状扭曲有关的结论．
용X사선쌍정연사대기원분자속외연(GS-MBE)제비적타/규단주기초정격(SPS)양품진행료분석．소유양품적타층후도고정위1．5단원자층，이규층후도위1．4～3．8 nm．대우규층후도소우2．4nm적양품래설，쌍정연사요파곡선중유초정격인기적연사봉교관，이차간불도간섭인기적정세결구，저표명초정격중가능존재위착급계면불평정．대규층교후(＞2．9 nm)적양품，요파곡선중초정격인기적연사봉흔착，이차유명현적유간섭산생적정세결구，표명차시초정격적질량교고，계면평정．대규층후도위2．1～2．9 nm적양품，초정격대응적연사봉가이분해위량개관도불등적자봉，단몰유정세결구출현．저개구간여문헌[1]보도적재형광광보발현적일개이상대출현구간완전상동．본실험적X사선쌍정연사측시여분석결과지지문헌[1]제출적차이상대여국부응력장인기적외연층정파랑상뉴곡유관적결론．
Ge/Si short period superlattice (SPS) samples consisting of 1.5 mono-layer Ge and 1.4 －3.8 nm thick Si layer grown by gas source molecular beam epitaxy (GS-MBE) were studied by double crystal X-ray diffraction. For SPS samples with Si layer less than 2.4 nm, the satellite peaks caused by SPS structure in the rocking curve are quite broad and without fine interference structure. For SPS samples with thick Si layer, the rocking curves are sharp and fine interference structures exist. For SPS samples with Si layer thickness (Lsi) between 2.1 nm and 2.9 nm, both broad and sharp peaks exist but without fine structure. Our results strongly support H.Sunamura's suggestion that the abnormal photoluminescence band in such SPS structure is caused by waviness formation of epi-layer due to vertical correlation of thickness fluctuations by local strain field.