| 1. |
- Zhao, Qingxiang, 1962, et al.
(författare)
-
Nitrogen incorporation in GaNas layers grown by molecular beam epitaxy
- 2006
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:3, s. 31907-1-31907-3
-
Tidskriftsartikel (refereegranskat)abstract
- GaNAs/GaAs quantum wells with high N concentrations, grown by molecular beam epitaxy, have been investigated by secondary-ion mass spectrometry (SIMS), high resolution x-ray diffraction (XRD), and photoluminescence (PL) measurements. The substitutional N concentration in an 18 nm thick strained GaNAs layer varies from 1.4% to 5.9% when the growth rate is reduced from 1 to 0.2 μm/h. By further reducing the growth rate, more N can be incorporated but relaxation occurs. Both the total N concentration, deduced from SIMS measurements, and the substitutional N concentration, deduced from XRD measurements, increase with reduced growth rate. By comparing the SIMS and XRD results, we found that a large amount of N was not in substitutional position when the substitutional N concentration is high (≫4%). The experimental results also show that there is no detectable change of total and substitutional N concentrations, within the instrument resolutions, after rapid thermal annealing at 700 °C for 30 s. However, PL measurements show a strong blueshift of the emission wavelength after annealing and the PL intensity increases by more than one order of magnitude.
|
|
| 2. |
- Fu, Ying, et al.
(författare)
-
Energy band structure and spectral gain characteristics of dilute-nitride zinc blende InGaNAs quantum wells embedded in GaAs and GaNAs barriers
- 2006
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 100:7
-
Tidskriftsartikel (refereegranskat)abstract
- The spectral gain characteristics of dilute-nitride zinc blende InxGa1-xNyAs1-y quantum wells embedded in GaNy1As1-y1 barriers have been investigated experimentally and theoretically. Two samples, both with the gain peak at 1300 nm, were studied for comparison. One has a high nitrogen concentration in the quantum well with the surrounding barriers being pure GaAs. The other has a lower and uniform nitrogen concentration in the quantum well and the barriers (GaNAs barriers). Measurements show the redshift of the gain peak induced by the incorporation of nitrogen and difference in the spectral gain characteristics. The energy band structures and spectral gain characteristics are analyzed theoretically using the standard eight-band k center dot p theory. It is shown that the introduction of nitrogen atoms in the GaAs barriers reduces the barrier height for the central quantum well so that the energy sublevels in the conduction band becomes condensed. The condensation of the conduction-band energy sublevels reduces the peak gain and makes the gain spectrum narrower, in agreement with measurements.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Modh, Peter, 1968, et al.
(författare)
-
Linear Cascade VCSEL Arrays With High Differential Efficiency and Low Differential Resistance
- 2006
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 18:1, s. 100-102
-
Tidskriftsartikel (refereegranskat)abstract
- We have fabricated monolithic linear cascade ver- tical-cavity surface-emitting laser (VCSEL) arrays intended for low loss fiber-optic radio-frequency links. Arrays with up to four VCSELs connected in series, with a spacing of 250 m, were fab- ricated on an insulating substrate. A thick layer of BCB was used to facilitate series connection through contact metallization and enable high frequency operation. The threshold current is 0.6 mA, independent of the number of VCSELs in the array. Differential efficiency, maximum output power, voltage, and differential re- sistance scale linearly with the number of VCSELs. For a four VCSEL array, we achieve a high differential efficiency of 160%, a maximum output power of 24 mW, and a low differential resis- tance of 220 . Basic link measurements, using a series connected VCSEL array, a parallel fiber ribbon, and a parallel connected detector array revealed a differential current gain exceeding unity in the low frequency limit.
|
|
| 9. |
|
|
| 10. |
|
|
