Epitaxial growth of p+ silicon on a backside-thinned CCD for enhanced UV response

We have used low temperature molecular beam epitaxy to grow p+ silicon on a backside-thinned Reticon 512x5 12 CCD. The techniques for preparing the CCD for the growth and the processing conditions are discussed. A 50 A layer of silicon doped with 3x102 B/cm3 was grown at a substrate temperature of 450C. The ultraviolet quantum efficiency of the modified CCD was significantly higher than that of a CCD with an untreated back surface. Charging the back surface of the modified CCD with a Uv flood did not affect the quantum efficiency indicating that the bands were pinned by the added p+ layer. Gold contamination measured by secondary ion mass spectrometry to have a concentration of 1 x 1 0 18 cm3 near the back surface caused the UV quantum efficiency to be lower than optimum by reducing the minority carrier lifetime. 2.