Hydrogen profiling in amorphous silicon films and p-n junctions

Refractive index and absorption in boron-doped a-Sic: H using either diborane or trimethylboron as a doping gas

“…The remarkable independence of hydrogen content on boron doping in our samples contrasts with previous measurements in a-Si : H by Miiller, Demond, Kalbitzer, Damjantschitsch and Mannsperger (1980). This fact could be due to a lower effective diffusion length for out-diffusion of hydrogen in more void-rich material as compared to more compact material as stated by Beyer et al (1 989).…”

“…2, the correlation between optical gap and Ere, has also not previously been observed in all materials. For example, in pure a-Si : H doped with diborane, Ristein and Weiser (1985) found little variation in Ere, but a large increase in E , (more correctly f",). The latter they attributed to an increase of oscillator strength indicating a change of the covalent network due to a reduction of the average Si-Si bond length with boron doping.…”

“…(2), which could, however, not fully explain the large increase of fiE,. (Note: Ristein and Weiser (1985) determined their parameters Ere, and E , in a different way using the maximum of E~ and dispersion relations. However, on plotting their n(E) data in terms of eqn.…”

INJECTION LUMINESCENCE IN AMORPHOUS SILICON p+-i-n+JUNCTIONS

“…We observe EL efficiency vaiues ranging up to nEL = 0.1 nrpL , where n' is the effective PL efficiency for excitation light at Argon laser energy of 2.4egf: which has a penetration depth of % 1OOnm. The top (n+) layer in these junctions has negligible PL efficiency and hydrogen profiling data (4) show that it extends to a depth % 50nm. We estimate that the excitation light at 2.4eV is attenuated by a factor of 0.3 on passing through this layer, and this is confirmed by PL experiments on the change in PL efficiency (using i 2.4eV excitation) on etching away the n+ layer.…”

“…An equally good fit can be obtained for X = 150 2 10nm. Recent hydrogen profiling data on similar junctions (4) she$ that the p+ layer extends to a depth ?. 150nm.…”