Electronic structures of ternary-layered semiconductor TlGaSe sub(2) investigated by photoemission spectroscopy

Electronic structures of the ternary-layered semiconductor TlGaSe sub(2) have been investigated by hard and soft X-ray photoemission spectroscopies (HAXPES and SXPES). The spectral shape of all core levels obtained from HAXPES and SXPES can be represented by a symmetric Lorentzian, reflecting the semiconducting nature of TlGaSe sub(2). Peak positions of the same bulk components, obtained from HAXPES and SXPES, are almost the same. This suggests that the recoil effect is ignorable for TlGaSe sub(2) and that the HAXPES spectra of this material provide us the information on the intrinsic bulk electronic structures. The valence-band HAXPES spectrum is composed of two main features and is well reproduced by the theoretical calculation. The estimated value of 2.0 eV for the energy gap is consistent with the results from the optical measurements. ([copy 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)