Measurements of the p-n product in heavily doped epitaxial emitters

A new method is described for the measurement of the p-n product in the heavily doped epitaxial emitters of biopolar tansistors. Quantitative electron-beam-induced conductivity is used to determine the diffusion length in the emitter as well as the emitter thickness. I - V characterization and other standard methods are then used to measure the p-n product. The principal advantage of this method is that corrections for recombination in both the emitter and the base can be made based on measurements on identical regions of the same device. A key problem with other methods for determining the p-n product is their inability to separate changes in the p-n product (bandgap narrowing) from recombination, based on measurements taken on the same region of the device. New data for the p-n product at ∼ 1020.cm3free-carrier electron density are uniformly compared to other published data. The importance of the effective bandgap narrowing parameter both for comparing experimental data and for device modeling is stressed. Diffusion length measurements on the more heavily doped emitters yield lifetimes longer than expected based on published lifetimes determined by the decay of optical luminescence in heavily doped silicon. Possible reason for this difference are discussed and attributed to gettering in our samples.

[1]  R. Mertens,et al.  Heavy Doping Effects in Silicon , 1987, Advanced Silicon and Semiconducting Silicon-Alloy Based Materials and Devices.

[2]  M. Adler.  Achieving accuracy in transistor and thyristor modeling , 1981, 1978 International Electron Devices Meeting.

[3]  R. F. Wood,et al.  Optical Properties of Heavily Doped Silicon between 1.5 and 4.1 eV , 1981 .

[4]  P. Schmid,et al.  Optical absorption in heavily doped silicon , 1981 .

[5]  M. A. Shibib,et al.  On the deionization of impurities as an explanation for excess intrinsic carrier density in heavily doped silicon , 1980, IEEE Transactions on Electron Devices.

[6]  Gerald D. Mahan,et al.  Energy gap in Si and Ge: Impurity dependence , 1980 .

[7]  M.S. Adler,et al.  Measurement of heavy doping parameters in silicon by electron-beam-induced current , 1980, IEEE Transactions on Electron Devices.

[8]  R. Mertens,et al.  Measurement of the minority carrier transport parameters in heavily doped silicon , 1980, 1978 International Electron Devices Meeting.

[9]  G. Possin,et al.  Electron beam depth profiling in semiconductors , 1980 .

[10]  N. Nilsson,et al.  Measurement of Auger recombination in silicon by laser excitation , 1978 .

[11]  P. Landsberg,et al.  The first 70 semiconductor Auger processes , 1978 .

[12]  A. H. Marshak,et al.  Electrical current in solids with position-dependent band structure , 1978 .

[13]  A. H. Marshak,et al.  Carrier densities and emitter efficiency in degenerate materials with position-dependent band structure , 1978 .

[14]  J. Dziewior,et al.  Auger coefficients for highly doped and highly excited silicon , 1977 .

[15]  Chih-Tang Sah,et al.  A methodology for experimentally based determination of gap shrinkage and effective lifetimes in the emitter and base of p-n junction solar cells and other p-n junction devices , 1977, IEEE Transactions on Electron Devices.

[16]  P. Iles,et al.  Effect of impurity doping concentration on solar cell output , 1975 .

[17]  H. D. Barber.  Effective mass and intrinsic concentration in silicon , 1967 .

[18]  E H Putley,et al.  The Electrical Conductivity and Hall Effect of Silicon , 1958 .

[19]  William Shockley,et al.  The theory of p-n junctions in semiconductors and p-n junction transistors , 1949, Bell Syst. Tech. J..

[20]  G. Possin,et al.  Measurements of band gap narrowing in heavily doped epitaxial emitters and the modeling of heavily doped silicon , 1980, 1980 International Electron Devices Meeting.

[21]  A. Wieder,et al.  Arsenic emitter effects , 1978, 1978 International Electron Devices Meeting.

[22]  A. Aziza,et al.  Infrared Absorption in Heavily Doped n-Type Si , 1969 .