摘要
采用气相沉积法制备了WSe2二维纳米材料,对其低温光致发光谱进行了研究。结果表明:随着WSe2层数的增加,其光致发光强度单调下降;当WSe2层数从单层增加为双层时,其发光强度急剧下降,表明其能带结构已从直接带隙转变为间接带隙。进一步研究了双层WSe2的变温光致发光谱,发现随着温度的升高,双层WSe2发光峰中A峰峰位的变化基本符合半导体带隙的温度变化规律,而I峰峰位红移与温度基本成线性关系,表明双层WSe2同时存在间接和直接跃迁,且直接跃迁和间接跃迁特性不同。
We systematically studied the low-temperature (12 K) photoluminescence (PL) spectroscopies of WSe2 nanosheets prepared by vapor deposition technique. It is found that PL intensity monotonically decreases with the increasing of WSe2 nanosheet layers. In particular, the PL intensity dramatically decreased when the thickness of WSe2 films changed from monolayer to bilayer, which indicated that there is a direct-to-indirect transition in the band gap of WSe2 nanosheets. Then we focused on the variable temperature photoluminescence of the bilayer structure. When the temperature increases from 12 K to 300 K, the temperature-dependent evolution of the direct transition energy (peak A) is approximately consistent with the common formula obeyed by bulk semiconductors, while the indirect transition energy (peak I) can only be described by a linear relationship with temperature. This indicates that peak A and peak I have different transition characteristics and these two transition characteristics coexist in bilayer WSe2 simultaneously.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2014年第5期513-518,共6页
Chinese Journal of Luminescence
基金
国家自然科学基金(11074056,11374070,11104042)
国家重点基础研究发展计划(2011CB932800)资助项目
