Experimental studies of proton-implanted GaAs-AlGaAs multiple-quantum-well modulators for low-photocurrent applications

We describe the first attempts to control photocurrent, and thus power dissipation, in surface-normal multiple-quantum-well (MQW) modulators. We have made detailed experimental studies of proton-implanted p-i-n GaAs-Al/sub x/Ga/sub 1-x/As MQW modulators having barrier layers of x=0.3, 0.45, and 1.0. Structures were implanted to levels of 1/spl times/10/sup 12/ cm/sup -2/, 1/spl times/10/sup 13/ cm/sup -2/, and 1/spl times/10/sup 14/ cm/sup -2/. Photocurrent progressively decreased with increasing implant-dose and barrier mole fraction (x). Exciton linewidths showed a strong voltage and implant dose dependence, demonstrating a tradeoff between photocurrent and modulation performance. We obtained our best results with x=1.0 barriers. For example, 1/spl times/10/sup 13/ cm/sup -2/-implanted asymmetric Fabry-Perot modulators were realized in which the optical performance was similar to that of unimplanted devices. The photocurrent responsivity was, however, only 0.007 A/W at 12.5 V bias. We report measurements of carrier lifetime in these materials that show the reduction in photocurrent arises from a reduction in lifetime due to implant-induced damage. In addition, the reduced lifetime decreases the optically-excited quantum-well carrier population, leading to an increase in cw saturation intensity. Specifically, 1/spl times/10/sup 13/ cm/sup -2/-implanted devices with x=1.0 have a saturation intensity of roughly 45 kW/cm/sup 2/, while unimplanted devices have 3.5 kW/cm/sup 2/. Asymmetric self electro-optic effect devices (A-SEED's) are demonstrated, and power dissipation issues associated with the use of low-photocurrent modulators in integrated systems are discussed. >

[1]  D. Miller,et al.  High speed absorption recovery in quantum well diodes by diffusive electrical conduction , 1989 .

[2]  J. Rosenzweig,et al.  Subpicosecond carrier lifetimes in radiation‐damaged GaAs , 1991 .

[3]  P. Solomon,et al.  Perpendicular transport across (Al,Ga)As and the Γ to X transition , 1986 .

[4]  C. Burrus,et al.  Band-Edge Electroabsorption in Quantum Well Structures: The Quantum-Confined Stark Effect , 1984 .

[5]  Schneider,et al.  Thermionic emission and Gaussian transport of holes in a GaAs/AlxGa1-xAs multiple-quantum-well structure. , 1988, Physical review. B, Condensed matter.

[6]  Moore,et al.  Observations and calculations of the exciton binding energy in (In,Ga)As/GaAs strained-quantum-well heterostructures. , 1990, Physical review. B, Condensed matter.

[7]  T J Cloonan,et al.  Six-stage digital free-space optical switching network using symmetric self-electro-optic-effect devices. , 1993, Applied optics.

[8]  J. Harris,et al.  GaAs/AlAs quantum wells for electro-absorption modulators , 1992 .

[9]  T. K. Woodward,et al.  Point source heating effects in multiple quantum well modulators , 1992 .

[10]  J. Cunningham,et al.  Excitonic electroabsorption in extremely shallow quantum wells , 1990 .

[11]  Larry A. Coldren,et al.  Surface-normal electroabsorption reflection modulators using asymmetric Fabry-Perot structures , 1991 .

[12]  T. K. Woodward,et al.  Measurement of carrier escape rates, exciton saturation intensity, and saturation density in electrically biased multiple-quantum-well modulators , 1994 .

[13]  F.J. Leonberger,et al.  Optical interconnections for VLSI systems , 1984, Proceedings of the IEEE.

[14]  Jagdeep Shah,et al.  Ultrafast luminescence spectroscopy using sum frequency generation , 1988 .

[15]  R. Leibenguth,et al.  Low‐temperature‐grown GaAs quantum wells: Femtosecond nonlinear optical and parallel‐field transport studies , 1991 .

[16]  David A. B. Miller,et al.  Linear and nonlinear optical properties of semiconductor quantum wells , 1989 .

[17]  David A. B. Miller,et al.  Quantum well carrier sweep out: relation to electroabsorption and exciton saturation , 1991 .

[18]  T. K. Woodward,et al.  Operation of a fully integrated GaAs-Al/sub x/Ga/sub 1-x/As FET-SEED: a basic optically addressed integrated circuit , 1992, IEEE Photonics Technology Letters.

[19]  G. D. Boyd,et al.  Electro-absorption and refraction in Fabry-Perot quantum well modulators: a general discussion , 1992 .

[20]  T. Boykin,et al.  GaAs/AlAs quantum wells for electroabsorption modulators , 1992 .

[21]  David A. B. Miller,et al.  Simultaneous measurements of electron and hole sweep-out from quantum wells and modeling of photoinduced field screening dynamics , 1992 .

[22]  T. K. Woodward,et al.  Suppressed photocurrent multiple-quantum-well optical modulators by proton implantation , 1992 .

[23]  David A. B. Miller,et al.  Mode locking of semiconductor diode lasers using saturable excitonic nonlinearities , 1985 .