Band-edge excitons of few-layer nickel phosphorous trisulfide (NiPS₃) are characterized via micro-thermal-modulated reflectance (μTR) measurements from 10 to 300 K. Prominent μTR features of the A exciton series and B are simultaneously detected near the band edge of NiPS₃. The A exciton series contains two sharp A₁ and A₂ levels and one threshold-energy-related transition (direct gap, E_∞), which are simultaneously detected at the lower energy side of NiPS₃. In addition, one broadened B feature is present at the higher energy side of few-layer NiPS₃. The A series excitons may correlate with majorly d-to-d transition in the Rydberg series with threshold energy of E_∞ ≅ 1.511 eV at 10 K. The binding energy of A₁ is about 36 meV, and the transition energy is A₁ ≅ 1.366 eV at 300 K. The transition energy of B measured by μTR is about 1.894 eV at 10 K. The excitonic series A may directly transit from the top of valence band to the conduction band of NiPS₃, while the B feature might originate from the spin-split-off valence band to the conduction band edge. The direct optical gap of NiPS₃ is ~1.402 eV at 300 K, which is confirmed by μTR and transmittance experiments.

通过从10到300 K的微热调制反射率（μTR）测量来表征几层_三硫化镍磷（NiPS ₃）的带边激子。在该谱带附近同时检测到A激子系列和B的突出μTR特征。 NiPS边缘₃。该A激子系列包含两个尖锐阿₁和阿₂水平和一个阈值能量相关的过渡（直接带隙，ë _∞），它们在压区的低能量侧同时检测₃。另外，在几层NiPS ₃的较高能量侧存在一个加宽的B特征。A系列激子可能主要与d相关-到- d在里德伯串联的阈值能量过渡Ê _∞  ≅  1.511伏特以10A的K的结合能₁是约36兆电子伏，和跃迁能量阿₁  ≅  1.366 eV的在300K的跃迁能量μTR在10 K时测得的B的约1.894 eV。激子级数A可能直接从价带的顶部跃迁到NiPS ₃的导带，而B特征可能起源于自旋分裂价带。导带边缘。NiPS ₃在300 K时的直接光学间隙为〜1.402 eV，这由μTR和透射率实验证实。