Physical review volume 05, number january 15, 1957

PHYSICAL REVIEW VOLUME 105, NUMBER 2 JANUARY 15, 1957

Diffusion and Electrical Behavior of Zinc in Silicon
C. S. Fuller and F. J. Morin
Bell Telephone Laboratories, Murray HUI, New Jersey
(Received October 3, 1956)
Zinc has been diffused into Si single crystals and estimations of the diffusion constant and solubility have been obtained by conductivity measurements. In the range 1000-1300°C the diffusivity varies between 10^-eand 10^-7cm^{1 2}/sec. However, no definite trend with temperature could be established, presumably because of surface barriers on the Si. A maximum solubility of about 1.4X10¹⁷ cm^-3 occurs at 1350°C and retrograde behavior is observed.
Hall effect and conductivity measurements as functions of temperature have been made on Si crystals containing diffused Zn. One acceptor level only was found for Zn at 0.31 ev above the valence band. B, Ga Al, and As were used as doping impurities. The electronic levels of the doping acceptors were altered by the presence of Zn, suggesting compound formation between the acceptor atoms and Zn.

INTRODUCTION
E CAUSE of the high volatility of zinc at the temperatures (over 1400°C) employed in growing silicon single crystals, it has been difficult to produce crystals containing zinc by the conventional doping procedure. Early attempts to diffuse zinc into silicon showed the rate of diffusion at 1000 to 1300°C to be considerably higher than that found for zinc in ger­manium at 800 to 900°C.¹ That work also indicated that new electronic energy levels were introduced when zinc was diffused into silicon.² The present paper describes experiments in which zinc has been diffused into undoped silicon crystals and into crystals doped with boron, aluminum, gallium, and arsenic. The first part deals with diffusion and solubility, the second part with the electronic energy levels found.