论文标题
多型硒凝胶中的多型
Polytypism in Few-Layer Gallium Selenide
论文作者
论文摘要
甲烯烃（GASE）是分层的III金属单钙化物质之一，它在单层中具有间接带隙，并且与其他常规过渡金属二甲硅烷（TMD）（例如Mox2和Wx2和WX2）（x = s = s = s and SE）不同，散装中的直接带隙。已经报道了四种多型散装GASE，称为β-，epsilon-，γ-和delta-gase。由于不同的多型也会导致不同的光学和电气性能，即使对于相同的厚度，识别多型对于利用该材料进行各种光电应用至关重要。我们在GASE上进行了极化的拉曼测量，并发现了不同的层间振动模式的不同超低频率拉曼光谱，即使由于多种型的堆叠序列而导致相同的厚度。通过将超低频率的拉曼光谱与理论计算和高分辨率电子显微镜测量进行比较，我们确定了超低频拉曼光谱与三层GASE的堆叠序列之间的相关性。我们进一步发现，AB型堆叠比Gase中的AA'Type堆叠更稳定。
Gallium selenide (GaSe) is one of layered group-III metal monochalcogenides, which has an indirect bandgap in monolayer and direct bandgap in bulk unlike other conventional transition metal dichalcogenides (TMDs) such as MoX2 and WX2 (X=S and Se). Four polytypes of bulk GaSe, designated as beta-, epsilon-, gamma-, and delta-GaSe, have been reported. Since different polytypes result in different optical and electrical properties even for the same thickness, identifying the polytype is essential in utilizing this material for various optoelectronic applications. We performed polarized Raman measurement on GaSe and found different ultra-low-frequency Raman spectra of inter-layer vibrational modes even for the same thickness due to different stacking sequences of the polytypes. By comparing the ultra-low-frequency Raman spectra with theoretical calculations and high-resolution electron microscopy measurements, we established the correlation between the ultra-low-frequency Raman spectra and the stacking sequences for trilayer GaSe. We further found that the AB-type stacking is more stable than the AA'-type stacking in GaSe.
