Modification of the Surface Band-bending of a Silicon Ccd for Low-energy Electron Detection

Abstract

Silicon CCDs have limited sensitivity to particles and photons with short penetration depth, due to the surface depletion caused by the inherent positive charge in the native o:xide. Because of sulface depletion, 1ntcmally-gcncralcd electrons are trapped near the Jrradiated swface and therefore cannot be transported to the detection circuitry. This deleterious surface potential ran be elinunated by low-temperature molcculac beam epitaxial (MDE) growth of a delta-doped layer on the Si surface. Tlus effect has been demonstrated through achievement of 100% internal quantum efficiency for UV photons detected with delta-doped CCDs. In this paper, we will discuss the mod1ficatton of the band bending near the CCD swface by lowtemperature MBE and report the application of dcJta-doperl CCDs to low-energy electron detection. We show that modification of the surface can greatly improve sensitivity to lowenergy electrons. Measurements comparing the response of delta-doped CCDs with untreated CCDs were made in the 50 eV-1.S keV energy range. For electrons with energies below 300eV, the signal from untreated CCDs was below the detection limit for our apparatus, and data are presented only for the response of delta-doped CCDs at these energies. The effects of mu1uple electron hole pair (EHP) production and backscattering on the observed signals are

Cite this paper

@inproceedings{Smith1996ModificationOT, title={Modification of the Surface Band-bending of a Silicon Ccd for Low-energy Electron Detection}, author={Aim6e L. Smith and Qiuming Yu and Steven T. Elliott and Shouleh Nikzad}, year={1996} }