The sharp luminescence of

n

-Si(As):Yb at 1130nm is reported for the first time in this paper. Its half width is 23.2nm. The three weak peaks with wavelength of 1190nm(1.04eV)

1150nm(1.08eV) and 1100nm (1.13eV)

respectively

are also observed at the same time. However

the both peaks at 1190nm and 1100nm are observed only when the light signal is amplified. We think that the three lines are the phonon replicas.The experimental results demonstrate that the emission intensity at 1130nm increases with increasing Yb dose. For lower dopar.t ones

especially

the intensity is significantly increased with slightly increasing Yb dose. For the range of ion number between 5×10

12

to 1×10

13

the intensity is almostly proportional to Yb dose. The intersily increasing becomes gradual when Yb exceedes 1×10

13

ions cm

-2

.In order to find the emission evidence

the absorption and tramsmi-ssion spectra (ATS) for the host and the luminescent samples were measured

respectively. Due to having no similar data previously

therefore

ATS oi

n

-Si(As):Er is shown for comparison to

n

-Se(As):Yb. Via an analysis we concluded that:the emission at 1130nm in

n

-Si(As):Yb does not arise from Si bandside; the excited energy of He-Ne laser (632.8nm) is not decrectly absorbed by As impurity in Si; and it does not arise from the radiative transition

2

F

5/2

-

2

F

7/2

of Yb

3+

(4f

13

).Finally

we think that the emission is a result of both sensitizer Yb and activator As. Here Yb acts as a shallow acceptor and is in the vicinity of top of valent band in Si. The energy transfer procedure between Yb and As are discussed

and a four level luminescent mode is proposed. It is found that the luminescent efficiency can be improved by appropriate selection of concentration ratios between Yb and As.