Fully-screened polarization-induced electric fields in blue∕violet InGaN∕GaN light-emitting devices grown on bulk GaN

Phys. Status Solidi (c)

et al. 2007

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Optical gain and losses in semiconductor laser epilayers are of profound importance in device optimization. We used both parameters to estimate the potential of InGaN/GaN/AlGaN epitaxial system to be used as a laser structure emitting in a blue region. The sample was grown homoepitaxially by MOVPE technique on high quality bulk GaN substrates obtained in high pressure growth process. These structures are characterized by very low dislocation density (around 10 5 cm -2). As a result the reduction of a nonradiative recombination is expected which is reflected in reduced excitation pump power and gain saturation processes described by means of saturation length and a product of the latter and a maximum modal gain. To determine gain value and its saturation behavior a variable stripe length method is used employing one dimensional amplifier model. Maximum gain value of 190 cm -1 together with internal losses of 15 cmare determined for the studied structure. Low value of maximum saturation length of 320 um was found in our structures.

Section: Gain Measurementmentioning

confidence: 99%

Optical gain and saturation behavior in homoepitaxially grown InGaN/GaN/AlGaN laser structures

Świetlik

Phys. Status Solidi (c)

et al. 2007

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“…[13]. In the present work, we proceed to the interpretation of experimental results by recalling the abovementioned fact that a value of dE E /dp close to the value of 35 meV/GPa for bulk In 0.1 Ga 0.9 N indicates a lack of PIEF.…”

Section: Resultsmentioning

confidence: 89%

Screening of polarization induced electric fields in blue/violet InGaN/GaN laser diodes by Si doping in quantum barriers revealed by hydrostatic pressure

Franssen

Phys. Status Solidi (c)

et al. 2006

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By means of hydrostatic pressure-dependent measurements of the electroluminescence of blue/violet laser diodes with In 0.1 Ga 0.9 N/GaN active layers grown on bulk GaN it is shown that at conditions close to lasing threshold full screening of polarization-induced electric fields (PIEFs) is provided by injected charge. In contrast, in order to achieve PIEF screening at currents much below lasing threshold, Si doping of quantum barriers is seen to be necessary.

“…Efficient screening can be achieved by means of either high densities of injected charge or high doping densities of the barriers in the active region [11]. As was remarked above, we can discriminate between unscreened and screened QWs by inspecting the value of dE E /dp: if it agrees with the dependence displayed in Fig.…”

Section: Experimental Results: Pief Screening In Ingan Ledsmentioning

confidence: 93%

“…This effect becomes larger for increasing QW widths [10]. Please note here that in the case of an efficiently screened PIEF no reduction of dE E /dp with respect to dE G /dp can be expected, which provides us with a tool to discriminate between unscreened and screened QWs [11]. The fingerprint of the presence of PIEFs in a given heterostructure is a fast decrease of dE E /dp with increasing QW width.…”

Section: Experimental Results: Influence Of Piefs and In Content On Dmentioning

confidence: 96%

Investigation of polarization‐induced electric field screening in InGaN light emitting diodes by means of hydrostatic pressure

Franssen

Physica Status Solidi (b)

et al. 2006

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We show that the hydrostatic pressure coefficient dE E /dp of luminescence in In x Ga 1-x N epilayers is in the range 20 -38 meV/GPa for the entire alloy (0 ≥ x ≥ 1) and corresponds roughly to the bandgap increase with applied pressure. It is argued that lowering of dE E /dp in quantum structures of InGaN with respect to this range can be attributed to polarization-induced electric fields (PIEFs). Possible contribution to dE E /dp originating from In-segregation effects is of secondary importance. This information is used to investigate PIEF screening by free carriers in InGaN-based light emitting diodes (LEDs). We observe that Si doping at a level of 10 19 cm -2 of the barriers in the active region of such LEDs leads to a significant increase of dE E /dp as compared to LEDs with undoped barriers. This is evidence for efficient screening of PIEFs in the Si-doped devices.