Growth of delta-doped layers on silicon CCD/S for enhanced ultraviolet response

US5376810A · kind A · utility

Assignee

• CALIFORNIA INSTITUTE OF TECHNOLOGY · US

Inventors

• Michael E. Hoenk · Pasadena, US
• Paula J. Grunthaner · Glendale, US
• Frank J. Grunthaner · Glendale, US
• Robert W. Terhune · Pasadena, US
• Michael H. Hecht · Los Angeles, US

Key dates

• Filing date: Dec 21, 1993
• Grant date: Dec 27, 1994
• Expiry date: Dec 21, 2013

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F39/15

Abstract

The backside surface potential well of a backside-illuminated CCD is confined to within about half a nanometer of the surface by using molecular beam epitaxy (MBE) to grow a delta-doped silicon layer on the back surface. Delta-doping in an MBE process is achieved by temporarily interrupting the evaporated silicon source during MBE growth without interrupting the evaporated p+ dopant source (e.g., boron). This produces an extremely sharp dopant profile in which the dopant is confined to only a few atomic layers, creating an electric field high enough to confine the backside surface potential well to within half a nanometer of the surface. Because the probability of UV-generated electrons being trapped by such a narrow potential well is low, the internal quantum efficiency of the CCD is nearly 100% throughout the UV wavelength range. Furthermore, the quantum efficiency is quite stable.