Linear Metal Atom Chain on GaN(0001) by Chemical Vapor Deposition

Chien-Hua Lung,Shie-Ming Peng,Che-Chen Chang

doi:10.1021/jp047324k

Abstract

The adsorption, reaction, growth, and the bonding configuration of a trinuclear linear metal atom chain complex, tetrakis(2,2‘-dipyridylamino)chromium(VI) chloride (DPCC, Cr3(μ3-dpa)4Cl2), on the GaN(0001) surface at 110 K were studied using synchrotron-induced X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS). XPS studies revealed three Cr chemical states of equal surface population present on the sample surface exposed to DPCC of low doses. The SIMS spectra showed main signals contributed from the sputter desorption of pyridine and the dipyridylamino ligand. Studies on small model molecules, such as pyridine and dipyridylamine (Hdpa), exposed to the sample surface showed that upon adsorption at 110 K, these small molecules were present on the sample surface in the molecular form only. They yielded the molecule-Ga adducts formed during SIMS detection. The absence of these adduct signals in the SIMS spectra taken from the DPCC-exposed surface indicated that DPCC chel...

Highlights

The last 40 years have witnessed astonishing advances in the field of microelectronics
Comparing with the secondary ion mass spectrometry (SIMS) spectra taken from the surface exposed to pyridine and dipyridylamine, respectively, showed that the major peaks observed in the SIMS spectra of DPCC on the GaN surface were not due to the production on the surface of the DPCC fragments in a series of decomposition reactions
Results from synchrotron-induced X-ray photoelectron spectroscopy (XPS) studies revealed three Cr chemical states, instead of two predicted based on the Cr chemical structure of bonding in the free DPCC, present in the system of DPCC of low doses adsorbed on the GaN surface

Summary

Introduction

The last 40 years have witnessed astonishing advances in the field of microelectronics. In the case when the DPCC chelate is positioned with its molecular axis tilted away from the surface, the Cr-N bond between the top terminal Cr atom in the central metal chain and the pyridyl group of the dpa ligand is more exposed to the probe ions for cleavage.

Results

Conclusion