Position of the degradation and the improved structure for the buried crescent InGaAsP/InP (1.3 μm) lasers
TL;DR: In this article, a degradation of the buried crescent (BC) InGaAsP/InP laser was found when the p−n junction plane coincides with the surface exposed in the high-temperature H2 ambient before the melt contact during the liquid phase epitaxial growth.
Abstract: We have found a degradation of the buried crescent (BC) InGaAsP/InP lasers that occurs when the p‐n junction plane coincides with the surface exposed in the high‐temperature H2 ambient before the melt contact during the liquid phase epitaxial growth. To eliminate the degradation, we have fabricated a new structure of the BC laser and have obtained stable cw operation at 80 °C.
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TL;DR: In this article, a defect mechanism associated with the gradual degradation of CSBH is discussed, which is characterized by a gradual increase in room-temperature threshold current, a decrease in external quantum efficiency, typically a drop in peak value of dL/dI greater than 25%, and a large peak in forward voltage at low current, indicating a change in junction characteristics.
Abstract: Channeled-substrate buried heterostructure (CSBH) lasers which were purged from populations undergoing high reliability qualification have been studied in detail. Gradual and rapid degradation mechanisms leading to accelerated aging failure modes have been analyzed by transmission electron microscopy, convergent beam electron diffraction, electroluminescence, energy dispersive x-ray analysis, and chemical etching. The gradual degradation mode of CSBH lasers is characterized by (1) a gradual increase in room-temperature threshold current; (2) a decrease in external quantum efficiency, typically a drop in peak value of dL/dI greater than 25%; (3) a drop in forward voltage at low current, indicating a change in junction characteristics; (4) a large peak inI(dV/dI) below threshold (at around 3 mA); and (5) an enhancement in the peak in I2(d2V/dI2) at laser threshold. A defect mechanism associated with the gradual degradation begins with a nucleation of extrinsic dislocation loops along the V-groove {111} p-n–type sidewall interfaces between the Cd-diffused p-InP and liquid-phase-epitaxial-grown n-InP buffer inside the groove. These dislocation loops subsequently grow out of the interfaces into the n-InP buffer region in the direction of minority-carrier injection, indicating a nonradiative recombination-assisted defect growth process. For those loops which enter the quaternary active region near the tip of the active crescent, the growth rate along the (001) and (010) planes is greatly enhanced and the loops eventually cut across the active stripe and become dark-line defects, as confirmed by electroluminescence. Nucleation of dislocation loops is not observed along the {111} p-p–type sidewall interfaces above the active stripe. The fact that the dislocation loops are all extrinsic in nature implies that the {111} sidewall interfaces as well as the quaternary active region contain a high density of interstitials. The possible causes for the generation and growth of the dislocation loops and the high density of point defects are discussed. The rapid degradation mode of the CSBH laser is characterized by a sudden drop in light intensity during the aging process. The associated defect mechanism starts with localized melting at the mirror facet or inside the lasing cavity. A metal-rich droplet subsequently forms which propagates along the center of the active stripe in the direction towards the cavity center via a meltback-regrowth process; i.e., material melts in front of the droplet and regrows after it propagates by. The nonideal condition of regrowth results in the formation of a wormlike defect composed of a cylinder of defective materials bounded by an off-stoichiometric interface. The wormlike defect is dark under electroluminescence. Complicated dislocation structures can also be grown from the wormlike defect under a nonradiative recombination-assisted defect growth process. These phenomena are presented and discussed.
49 citations
TL;DR: In this paper, a failure mode connected to the active region, not to the burying region, is observed in InGaAsP/InP buried heterostructure lasers, and degradation is related to a decrease in the carrier lifetime or decrease in nonradiative lifetime due to degradations at the edges of the active regions.
Abstract: In InGaAsP/InP buried heterostructure lasers, a failure mode connected to the active region, not to the burying region, is observed. The degradation is related to a decrease in the carrier lifetime or a decrease in nonradiative lifetime due to degradations at the edges of the active region. Practically, the bad devices may be screened out by the hard screening method, however, the failure mode could determine the reliability of the devices under high‐temperature or high‐power operation, so care should be taken during forming the mesa and a regrowth of the burying layer.
41 citations
TL;DR: In this paper, the InGaAsP P-substrate buried crescent (PBC) laser diodes have been used to achieve a maximum CW temperature of 135°C.
Abstract: High performance of newly developed InGaAsP P-substrate buried crescent (PBC) laser diodes is described. It is shown that the PBC laser has superior characteristics to the conventional buried crescent (BC) laser with n-InP substrate. The maximum output power of 140 mW under a CW condition is realized at room temperature. CW light output power of 10 mW up to 110°C is achieved. A maximum CW temperature of 135°C is obtained. Stable CW operations have been confirmed in 70°C 5-mW and 70°C 20-mW aging tests. The reason for the high performance is discussed in relation to the leakage current which flows through the current blocking layers.
34 citations
TL;DR: In this paper, the fabrication procedure, designing of an active region and a p-n-p-n current blocking structure, characteristics and the aging results of an InGaAsP/InP buried crescent (BC) laser diode are described.
Abstract: The fabrication procedure, designing of an active region and a p-n-p-n current blocking structure, characteristics and the aging results of an InGaAsP/InP buried crescent (BC) laser diode are described. The BC laser diodes exhibit high laser performances, such as a low-threshold current, a fundamental transverse mode oscillation with linear light output-current characteristics. CW operation at as high as 100°C is achieved with a junction up configuration as a result of the improvement in the current blocking structure. A stable CW operation at 80°C has been realized with a constant optical output power of 5 mW.
28 citations
TL;DR: In this paper, the authors investigated the relationship between degradation and device characteristics in InGaAsP/InP buried heterostructure lasers, and found that when leakage current increases during aging, devices having a low initial voltage also tend to degrade to a large extent.
Abstract: Correlations between degradation and device characteristics are investigated in InGaAsP/InP buried heterostructure lasers. The logarithm of threshold‐current increase rates is confirmed to be proportional to the voltage decrease at low current when injected carrier lifetime decreases during aging. When leakage current increases during aging, devices having a low initial voltage also tend to degrade to a large extent. These correlations hold within an operating range limited by the device structure and the material used during fabrication.
25 citations
References
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TL;DR: In this article, a V-grooved substrate buried-heterostructure laser emitting at 1.3?m wavelength is described and the active layer is buried in the V-shaped groove.
Abstract: A V-grooved substrate buried-heterostructure laser emitting at 1.3 ?m wavelength is described. The active layer is buried in the V-shaped groove. A CW threshold current of 10~20 mA is obtained and a far-field pattern free from irregularity and peak shift is realised. Damped relaxation oscillation and stable aging characteristics are obtained.
84 citations
TL;DR: In this paper, an InGaAsP/InP laser diode emitting at 1.3 μm with a crescent shaped active region is described. The active region was completely embedded in InP by a two-step LPE technique, and a double current confinement scheme was incorporated with two reverse biased p-n junctions at both sides of the active layer.
Abstract: An InGaAsP/InP laser diode emitting at 1.3 μm with a crescent shaped active region is described. The active region is completely embedded in InP by a two-step LPE technique, and a double current confinement scheme is incorporated with two reverse biased p-n junctions at both sides of the active layer. A threshold current as low as 20 mA has been achieved in CW operation at room temperature. Fundamental transverse mode operation with linear light output-current characteristics and single longitudinal mode oscillation have been obtained.
54 citations
TL;DR: In this paper, an InGaAsP/InP injection laser is described, in which a crescent-shaped active region is completely embedded in InP by the etch-and-fill l.p.
Abstract: An InGaAsP/InP injection laser is described in which a crescent-shaped InGaAsP active region is completely embedded in InP by the etch-and-fill l.p.c. technique and a double current confinement scheme is incorporated with two reverse-biased p-n junctions on both sides of the active layer. The best laser has the very low threshold current of 28 mA c.w. at room temperature, and shows stable single-mode c.w. operation up to about twice the threshold current.
40 citations
TL;DR: InP DH was used for life tests of InP DH lasers fabricated from InP-1-x/1-y/InP-DH laser arrays as discussed by the authors, and
Abstract: Life tests of In1-x Gax Asy P1-y /InP DH lasers fabricated from
40 citations
TL;DR: In this article, a 1.3 µm InGaAsP InP buried heterostructure laser with optimized stripe widths of 1.5 µm was used for high temperature operation up to 95°C.
Abstract: A marked reduction of cw threshold current, to as low as 10 mA at 25°C, was achieved in 1.3 µm InGaAsP InP buried heterostructure lasers with optimized stripe widths of 1.5–2.5 µm, resulting in the feasibility of high temperature operation up to 95°C. For the first time, high temperature cw agings at 50 and 70°C were carried out for lasers in this wavelength region, with successful results.
25 citations