Cathodoluminescence spectroscopy was used here, for the first time, to detect base-dopant out-diffusion which was caused by current stress in Be-doped heterojunctions. The results showed that diffusion of the base dopant along the growth direction of the device structure occurred during stressing. This conclusion was confirmed by secondary ion mass spectrometry. Integrated cathodoluminescence-intensity variations which were produced by the stress suggested that a mechanism of recombination-enhanced impurity diffusion was responsible for the Be diffusion.
Cathodoluminescence Evidence of Stress-Induced Out-Diffusion of Beryllium from AlGaAs/GaAs Heterojunction Bipolar Transistors. M.Borgarino, G.Salviati, L.Cattani, L.Lazzarini, C.Z.Fregonara, F.Fantini, A.Carnera: Journal of Physics D, 1998, 31[21], 3004-8
Table 1
Diffusivity of Al in AlAs/GaAs
Si (/cm3) | Temperature (C) | D (cm2/s) |
5 x 1017 | 900 | 6.1 x 10-17 |
5 x 1017 | 850 | 3.0 x 10-17 |
1 x 1018 | 795 | 5.0 x 10-17 |
2 x 1018 | 750 | 6.6 x 10-17 |
2 x 1018 | 750 | 5.4 x 10-17 |
5 x 1018 | 700 | 4.2 x 10-17 |
5 x 1017 | 795 | 2.3 x 10-18 |
2 x 1018 | 695 | 1.1 x 10-17 |
2 x 1018 | 700 | 5.6 x 10-18 |
5 x 1018 | 650 | 5.6 x 10-18 |
1 x 1018 | 745 | 2.6 x 10-18 |
2 x 1018 | 655 | 1.0 x 10-18 |
2 x 1018 | 655 | 7.3 x 10-19 |
2 x 1017 | 900 | 1.2 x 10-17 |
5 x 1017 | 745 | 3.6 x 10-19 |
- | 850 | 4.2 x 10-20 |
- | 800 | 2.6 x 10-20 |