Self-consistent gain analysis of type-II ‘W’ InGaN–GaNAs quantum well lasers

Abstract

Articles you may be interested inThermal dependence of the optical gain and threshold current density of GaInNAs/GaAs/AlGaAs quantum well lasers Effect of (1010) crystal orientation on many-body optical gain of wurtzite InGaN/GaN quantum well Type-II InGaN-GaNAs quantum wells ͑QWs͒ with thin dilute-As ͑ϳ3%͒ GaNAs layer are analyzed self-consistently as improved III-nitride gain media for diode lasers. The band structure is calculated by using a six-band k · p formalism, taking into account valence band mixing, strain effect, spontaneous and piezoelectric polarizations, as well as the carrier screening effect. The type-II InGaN-GaNAs QW structure allows large electron-hole wave function overlap by confining the hole wave function in the GaNAs layer of the QW. The findings based on self-consistent analysis indicate that type-II InGaN-GaNAs QW active region results in superior performance for laser diodes, in comparison to that of conventional InGaN QW. Both the spontaneous emission radiative recombination rate and optical gain of type-II InGaN-GaNAs QW structure are significantly enhanced. Reduction in the threshold current density of InGaN-GaNAs QW lasers is also predicted.FIG. 4. ͑Color online͒ Spontaneous emission spectra for type-I In 0.24 Ga 0.76 N QW and type-II In 0.15 Ga 0.85 N-GaN 0.97 As 0.03 QW as increasing carrier density n = ͑1-5͒ ϫ 10 19 cm −3 with self-consistent model calculation.

First-principle natural band alignment of GaN / dilute-As GaNAs alloy

“…The use of AlGaN tensile barriers 44 will potentially result in the strain compensation and improved barrier confinement in type-I GaNAs QW structure. In addition, the use of dilute-As GaNAs alloy had previously been suggested in type-II InGaN / dilute-As GaNAs QWs 27,28 for addressing the charge separation issue in the QW. The use of dilute-As GaNAs with large valence band offset in type-II QW structure results in strong hole confinement, which in turn increase the electron-hole wavefunction overlap in polar InGaN-based QWs resulting in improved spontaneous emission rate and optical gain.…”

“…The advantage of this alignment for a material system is that it can be directly connected to the physical situation of photoelectrode 33,34 and active regions for lasers or LEDs. 27,28 In the potential line-up method, the calculation of valence band offset (VBO) between two different materials is a combination of two terms which are the band structure term (∆E v ) and the electrostatic term (∆V). For the band structure term, it is defined as the difference between the top of the valence bands of two bulk materials with respect to the average electrostatic potential at core.…”

“…Dilute-arsenic GaNAs-based alloy has yet to be implemented into devices and the available literature published on this alloy subject is severely limited. 5,[19][20][21][22][23][24][25][26][27][28] Li and co-workers first succeeded in incorporating As into thin film GaN through metal-organic chemical vapor deposition (MOCVD), and the redshift of band gap energy of the dilute-As GaNAs alloy was observed in the photoluminescence study. 5 Further studies have also shown successful incorporation of As-content up to 7% into GaN material through MOCVD, 20 and synthesis of GaNAs alloy in full composition range through molecular beam epitaxy (MBE) was recently reported.…”

On the Effect of Step-Doped Quantum Barriers in InGaN/GaN Light Emitting Diodes

“…The spatial separation of the electron-hole wave functions can be reduced also by employing either the ternary InGaN substrate [21] or the electro-plated Ni metal substrate [22]. Recently, c-plane III-Nitride quantum wells with embedded "delta" novel materials have proved to be effective in enhancing the electron-hole wave function overlap, therefore increasing the radiative recombination rates [23]- [26]. The strain induced spatial separation of electron-hole wave functions can further be completely eliminated in the non-polar quantum wells and increased radiative recombination rates can thus be obtained [27], [28].…”

On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes

“…Some of the main issues affecting the LED performance and the corresponding solutions reported in the literature include: (1) Polarization induced quantum confined Stark effect (QCSE) in quantum wells (QWs) separates electrons and holes spatially and reduces the optical matrix element. Staggered InGaN QWs [2] and type-II QWs [3,4] have been proposed to improve the optical matrix element. (2) Electron overflow from the QWs to the p-GaN region gives rise to the quantum efficiency droop at high current density [5,6].…”