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Ambipolar Lifetimes in GaAs/AlGaAs Self Electro-Optic Effect Devices

  • V. Swaminathan (a1), J. M. Freund (a1), M. W. Focht (a1), G. D. Guth (a1), G. J. Przybylek (a1), L. E. Smith (a1), R. E. Leibenguth (a1) and L. A. D'Asaro (a2)...


The forward current-voltage (I-V) characteristics of GaAs/AlGaAs Self Electro-optic Effect Device (SEED) p-i-n diodes were measured. The I-V curves exhibited a diode like behavior with an ideality factor of 2 for voltages in the range 0.5–1.25V. In this region, the diode series resistance varied inverse proportional to the forward current with the constant of proportionality being equal to this voltage drop in the i-region. From an analysis of the experimentally obtained voltage drop, the ambipolar lifetime was determined. For the standard device whose i-region had a multi quantum well structure consisting of 60 periods of 100Å undoped GaAs wells and 65Å undoped Al0.30Ga0.70 As barriers, the ambipolar lifetime was found to be 79.6±3 psec for a 30×30 μm2 mesa device and 92 ± 4 psec for a 100×100 μm2 mesa device. When the barrier width was reduced to 35Å or when the barrier Al composition decreased to 0.2, no significant change in the ambipolar lifetime was measured. Since previous measurements have indicated that decreasing the barrier width or height greatly enhances carrier escape from the wells during the operation of the GaAs/AlGaAs p-i-n diode as a photodetector, it is inferred that the carrier escape and collection times are smaller than ∼ 80–90 psec.



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[1] For a recent review see Miller, D. A. B., “Quantum Well Self Electro optic Effect Devices”, Optical and Quantum Electronics, 22, S61S98 (1990).
[2] Lentine, A. L., Chirovsky, L. M. F, D'Asaro, L. A., Tu, C. W., and Miller, D. A. B., “Energy Scaling and Subnanosecond Switching of Symmetric Self Electro optic Effect DevicesIEEE Photonics Technology Letters, 1, 129131 (1989).
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[4] Boyd, G. D., Fox, A. M., Miller, D. A. B., Chirovsky, L. M. F., D'Asaro, L. A., Kuo, J. M., Kopf, R. F., and Lentine, A. L., “33ps Optical Switching of Symmetric Self Electro-optic Effect DevicesAppl. Phys. Lett., 57, 18431845 (1990).
[5] Morgan, R. A., Freund, J. M., Chirovsky, L. M. F., D'Asaro, L. A., Kopf, R. F., and Kuo, J. M., “Improvements in Self Electro-optic Effect Devices using Reduced Barrier Multiple Quantum WellsLEOS '90 Conference Digest, Paper OE8.2, p. 156 (1990).
[6] Chirovsky, L. M. F., D'Asaro, L. A., Tu, C. W., Lentine, A. L., Boyd, G. D., and Miller, D. A. B., “Batch Fabricated Symmetric Self Electro-optic Effect Devices” Proc. on Photonic Switching, eds. Midwinter, J. E. and Hinton, H. S., vol. 3 (Optical Society of America, Washington, D.C., 1989) p. 26.
[7] Swaminathan, V., Freund, J. M., Chirovsky, L. M. F., Harris, T. D., Kuebler, N. A., and D'Asaro, L. A., “Evidence for Surface Recombination at Mesa Sidewalls of Self Electro-optic Effect DevicesJ. Appl. Phys., 68, 41164118 (1990).
[8] Chiang, Y. S., and Denlinger, E. J., “Low Resistance All-Epitaxial PIN Diodes for Ultra-High-Frequency ApplicationsRCA Rev. 38, 390405 (1977).
[9] Sze, S.M., “Physics of Semiconductor Devices2nd edition (Wiley, New York, 1981) p. 120.
[10] Uchiki, H., Kobayashi, T., and Tokuraga, E., “Carrier Diffusion and Trapping by Quantum WellsPhys. Stat. Solidi 150B, 667672 (1988).
[11] Luther, L. C. unpublished. From Hall measurements on single layers of n- or p-type (n,p ∼1015 -1016 cm−3) GaAs and AlxGa1−xAs (x ∼ 0.1 – 0.3), the room temperature electron and hole mobilities are determined to be ∼ 2000 cm2 V−1 sec−1 and ∼ 200 cm2 V−1 sec−1, respectively.
[12] For the low barrier structure we did not observe the dependence of τa on mesa size due to recombination at mesa sidewalls as we did for the standard and thin barrier structure. We believe that this is perhaps fortuitous and not caused by the change in the MQW structure.
[13] A similar conclusion was reached independently by optical measurements on thin and low barrier devices. R.A. Morgan, private communication.

Ambipolar Lifetimes in GaAs/AlGaAs Self Electro-Optic Effect Devices

  • V. Swaminathan (a1), J. M. Freund (a1), M. W. Focht (a1), G. D. Guth (a1), G. J. Przybylek (a1), L. E. Smith (a1), R. E. Leibenguth (a1) and L. A. D'Asaro (a2)...


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