Photoemission studies of semiconductor nanocrystals

Technical Report · Tue Apr 01 04:00:00 EST 1997

DOI:https://doi.org/10.2172/603477· OSTI ID:603477

Hamad, K. S. ^[1]; Roth, R. ^[1]; Alivisatos, A. P. ^[1]

---

1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Design Inst., Materials Science Div.

Semiconductor nanocrystals have been the focus of much attention in the last ten years due predominantly to their size dependent optical properties. Namely, the band gap of nanocrystals exhibits a shift to higher energy with decreasing size due to quantum confinement effects. Research in this field has employed primarily optical techniques to study nanocrystals, and in this respect this system has been investigated extensively. In addition, one is able to synthesize monodisperse, crystalline particles of CdS, CdSe, Si, InP, InAs, as well as CdS/HgS/CdS and CdSe/CdS composites. However, optical spectroscopies have proven ambiguous in determining the degree to which electronic excitations are interior or surface admixtures or giving a complete picture of the density of states. Photoemission is a useful technique for understanding the electronic structure of nanocrystals and the effects of quantum confinement, chemical environments of the nanocrystals, and surface coverages. Of particular interest to the authors is the surface composition and structure of these particles, for they have found that much of the behavior of nanocrystals is governed by their surface. Previously, the authors had performed x-ray photoelectron spectroscopy (XPS) on CdSe nanocrystals. XPS has proven to be a powerful tool in that it allows one to determine the composition of the nanocrystal surface.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: USDOE
• OSTI ID: 603477
• Report Number(s): LBNL--39981; ON: DE97007345; CNN: Grant DMR-9505302
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CADMIUM SELENIDES
CADMIUM SULFIDES
COMPOSITE MATERIALS
ELECTRONIC STRUCTURE
ENERGY GAP
INDIUM ARSENIDES
INDIUM PHOSPHIDES
PARTICLES
PHOTOEMISSION
SEMICONDUCTOR MATERIALS
SILICON