Surface Energy Band and Electron Affinity of Highly Phosphorous-doped Epitaxial CVD Diamond

Abstract

The surface energy band diagrams and the electron affinity of hydrogen-terminated and oxygen-terminated highly phosphorous-doped single crystal diamond (111) surfaces have been studied by ultraviolet photoelectron spectroscopy, secondary electron spectroscopy, X-ray photoelectron spectroscopy and photoemission electron microspectroscopy. A hydrogen-terminated boron-doped diamond (001) surface was used as a reference of surface energy band diagram. The electron affinity of the H-terminated heavily P-doped diamond was determined to be 0.2 ± 0.15 eV, thus close to zero. The electron affinity of the O-terminated highly P-doped diamond was determined to be 0.0 ± 0.15 eV, thus can be negative. However, the surface energy bands for the two highly P-doped samples were found to have large amounts (3 eV) of upward bending toward surface.

Investigation of electron emission site of p–i–n diode-type emitters with negative electron affinity

“…Taking our photoemission results for NEA into account, the contribution of the n + -layer with NEA to electron emission is not expected. 4,[6][7][8][9][10] In addition, the larger the carrier diffusion length, the larger the contribution of the electron emission with NEA. 4,10,16) It is reasonable that the diffusion lengths of free electrons and/or free excitons in the i-layer are larger than those in the p-layer.…”

“…In addition, we previously revealed that an n-type surface with NEA induced by hydrogen termination does not show electron emission from the bulk, where a large upward band bending might exist. [7][8][9][10] In this study, we designed structures of p-i-n diode emitters for investigating emission sites. We changed the periphery length of p-i-n mesa diodes while maintaining the top area.…”

Mechanism of Field Emission from a Highly Phosphorous-Doped Chemical Vapor Deposition Diamond (111) Surface

“…First, we pay attention to the relationship of the energy positions of field emission and photoemission peaks with those of work function and electron affinity of the P-doped (111) surface. As already mentioned, and of highly Pdoped diamond (111) have been studied very recently 13) and it showed that and of a H-terminated heavily P-doped diamond are about 3.8 and 0.2 eV, respectively. If we place the photoemission peak about 1 eV above CBM at the surface, the field emission peak comes right on the sample surface E F .…”

“…[9][10][11] In the F-N analyses, the work function () and the electron affinity () of the surface were assumed to be identical to those of lightly P-doped 12) or intrinsic diamond (111) surfaces. and of highly P-doped diamond (111) have been studied very recently, 13) which showed that and of a H-terminated heavily P-doped diamond are $3:8 and $0:2 eV, respectively and that and of an O-terminated highly P-doped diamond are $3:9 and $0 eV, respectively. These values are quite different from those of lightly P-doped or intrinsic diamond (111).…”

“…Further, the surface energy bands for the two highly P-doped samples were found to have large amounts ($3 eV) of upward band bending toward surface. 13) In order to understand the mechanism of field emission, it is important to measure energy distribution of emitted electrons from the emission site and compare the EDC with EDC of photo-emitted electrons from the field-emission site itself. Therefore, microscopic electron spectroscopy is needed since field emission is often a spatially localized event while photoemission is a macroscopic event.…”