Energy distribution of thermally emitted negative particles from type Ia diamond (100)

This study explores the electron emission of natural, nitrogen-doped diamon d at elevated temperatures. The diamond was resistively heated up to 870 de greesC. Accruing negatively charged particles where accelerated by a bias v oltage of 30 V and the energy distribution is measured. The electrons are a nalysed by an electrostatic deflection resulting in an energy resolution of 70 meV. A hydrogen-free surface at a base pressure of 2.0 x 10(-9) mbar sh ows a very small emission. The energy distribution has its maximum at 2.5 e V and a FWHM of 0.52 eV. Beside the main emission peak, some smaller featur es are observable at higher energies. An atomic hydrogen supply at 1.9 x 10 (-5) mbar increases the emission by a factor of 30. With some delay to the hydrogen supply, a new low energy peak appears. The increase in intensity d uring hydrogen adsorption is explained by the occurrence of a negative elec tron affinity (NEA) of the hydrogen-covered diamond surface. The low-energy feature might be due to hydrogen ions, either desorbing from the surface o r from charge transfer during collisions of gas phase hydrogen with the dia mond surface. (C) 2001 Elsevier Science B.V. All rights reserved.