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ABSTRACT: We describe the effect of growth temperature on the optical absorption, gain, and threshold current density of 730-nm emitting, metal-organic vapor phase epitaxy (MOVPE) grown, InP-AlGaInP quantum-dot lasers. Decreasing the growth temperature from 750??C to 690??C leads to an increase in ground state absorption, while sufficient optical gain and low 300 K threshold current density is obtained in the growth temperature window between 710??C and 730??C . Wider (16 nm compared to 8 nm) interlayer barriers lead to lower threshold current density with 300 K values as low as 165 Acm<sup>-2</sup> for 2-mm-long lasers with uncoated facets.
IEEE Photonics Technology Letters 02/2010; · 2.19 Impact Factor
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ABSTRACT: GaInP/GaAs/GaInP double heterojunction bipolar transistors incorporating dead-space corrected composite collectors were investigated experimentally. The optimized DHBT with a 10-nm lowly doped GaAs spacer and a 5-nm highly doped GaInP spacer has extended the operating range of the collector-emitter voltage, V<sub>CE</sub> , by maximizing the collector-emitter voltage at the onset of the multiplication, V<sub>CE, onset </sub> , to 20 V, while minimizing the saturation voltage, V<sub>CE, sat </sub> (≪1 V) , and maintaining the nominal breakdown voltage, BV<sub>CEO</sub> , of the GaInP collector at 25 V. The design incorporating an Al <sub>0.11</sub> Ga <sub>0.89</sub> As spacer rather than a GaInP spacer within the lowly doped GaAs-GaInP composite collector demonstrated similar breakdown behavior.
Journal of Applied Physics 05/2007; · 2.17 Impact Factor
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ABSTRACT: Ga In P / Ga As / Ga In P double heterojunction bipolar transistor (DHBT) with an Al <sub>0.11</sub> Ga <sub>0.89</sub> As layer within lowly doped GaAs–GaInP composite collector was characterized. In comparison to an abrupt Ga In P / Ga As / Ga In P DHBT with saturation voltages in excess of 20 V , current gains of 25 at high biases, and breakdown voltages in the range of 22 V , the DHBT incorporating Ga As – Al <sub>0.11</sub> Ga <sub>0.89</sub> As – Ga In P composite collector has demonstrated lower saturation voltages of less than 6 V and high current gains of 50 without compromising the breakdown voltages of the GaInP collector. Al <sub>0.11</sub> Ga <sub>0.89</sub> As layer can thus provide an alternative design to effectively minimize the potential spike effects at the Ga As / Ga In P heterojunction.
Journal of Applied Physics 08/2006; · 2.17 Impact Factor
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ABSTRACT: We describe the growth, material characterization, and device characterization of InP-GaInP quantum-dot lasers for operation in the wavelength range 690-750 nm. We show that the growth conditions have a major influence on the form of the gain spectrum. Relatively flat gain can be achieved over a spectral width of 90 nm at 300 K using samples containing a bimodal distribution of dot sizes, or narrower gain spectra at shorter wavelength can be achieved by suppressing the bimodal distribution by using (211)B substrates. Optimization of samples grown on substrates with the growth surface of (100) misorientated by 10° toward [111] results in laser operation between 729 and 741 nm and with a room temperature threshold current density as low as 190 A·cm<sup>-2</sup> for a 2000-μm-long device with uncoated facets.
IEEE Journal of Selected Topics in Quantum Electronics 10/2005; · 3.78 Impact Factor
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ABSTRACT: InP quantum-dot lasers grown on GaAs substrates and emitting in the 730-740 nm band with threshold current density as low as 190 A cm<sup>-2</sup> for a 2000 μm-long device with uncoated facets are reported.
Electronics Letters 04/2005; · 0.96 Impact Factor
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ABSTRACT: We have measured the gain-current and gain-quasi–Fermi level separation characteristics for In P / Al Ga In P quantum-dot-laser structures. Saturation of the gain-current characteristics is apparent even though photoluminescence excitation spectroscopy measurements indicate that the 2D states are energetically distant from the dot states. The gain is reduced from the maximum value by the distribution of carriers in the excited dot states, the states in smaller dots and the 2D states.
Applied Physics Letters 02/2005; · 3.84 Impact Factor
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Applied Physics Letters 01/2005; 86(2). · 3.84 Impact Factor
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ABSTRACT: We optimize the gain of InP/GalnP dots by varying the growth rate, matrix material and substrate orientation. A 750 μm long laser with uncoated facets emitting at 688 nm has a threshold current density of 2.4 kAcm<sup>-2</sup>.
Lasers and Electro-Optics Society, 2004. LEOS 2004. The 17th Annual Meeting of the IEEE; 12/2004
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ABSTRACT: We have grown InP quantum dots with different rates and on substrates with different orientations. The growth conditions have a major influence on the form of the gain spectrum. Using a high growth rate on a 10° off (100) substrate we obtain a broad gain spectrum due to contributions from a bimodal dot size distribution whereas a sample containing mostly small dots, produced using (211) B substrates, has a narrower gain spectrum centered at a shorter wavelength of ∼700–710 nm . The modal gain saturates at a magnitude significantly smaller than the modal absorption, nevertheless the measured values of modal gain are sufficient to sustain laser action, and structures grown at high growth rate on 10° off (100) substrates are capable of providing laser devices operating in the region of 750 nm .
Applied Physics Letters 10/2004; · 3.84 Impact Factor
