The mechanism for the 1.54 mum luminescence of erbiumdoped porous silicon and the method of attaining a high efficiency.

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In the 1997 research year, Er, Yb, Nd as well as Ho were chosen as rare earth elements and were incorporated into porous silicon (PS) as well as crystalline silicon (c-Si) hosts.The 1.54 mum luminescence due to the 4f electron transition from Er-dope PS showed formerly a width of about 10nm. In this research period, we introduced a hydrogen plasma annealing at -1000ﾟC after Er incorporation and obtained spectra composed of sharp peaks whose full-width-at-half-maximu (FWHM) is less than 1nm. We explained that silicon oxide and amorphous silicon regions were etched off by the hydrogen plasma treatment and that the remained Er-doped silicon nanocrystals showed sharp peaks.These sharp luminescence peaks exibited a small thermal quenching. This was due to the increased bandgap of silicon nanocrystals : (Presented in the MRS 1997 Fall Meeting, and submitted to J.Apple.Phys.)We studied the Yb - 1.0 mum luminescenece from Yb doped PS as a function of host PS treatment processes. Pre-oxidation of PS resulted in the one-order increase in the Yb luminescence intensty. Measurements of the decay times of PS and Yb luminescence showed that the passivation of the dangling bonds of PS with oxygen reduced the nonradaitive recombination centers, which led to an increse in the enrgy transfer efficiency from PS to Yb. (presented in J.Appl.Phys.)We measured the decay time of Nd doped PS,and obtained the decay times of 200-300 mus for the 0.93 mum and 1.06 mum luminescence peaks. In colaboration with Dr.A.Polman of FOM institue in Amsterdam, Ho ions were inplanted into c-Si, and the luminescence at - 1.2 mum due to the 4f-electron transition was observed for the first time.