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    High mobility In<inf>0.30</inf>Ga<inf>0.70</inf>As MOSHEMTs on low threading dislocation density 200 mm Si substrates: A technology enabler towards heterogeneous integration of low noise and medium power amplifiers with Si CMOS
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    Abstract:
    An approach for heterogeneous integration of InGaAs MOSHEMTs and Si-CMOS is proposed and a high quality multi-layer transfer process is demonstrated in 200 mm wafer scale. Heterostructures for In0.30Ga0.70As MOSHEMTs were grown using MOCVD on 200 mm Si substrates with record low threading dislocation density of < 2 × 10 7 cm −2 . Devices with a Si-CMOS compatible front-end process were fabricated and the impact of the heterostructure design and doping on device performance is studied. Low subthreshold swing with minimum (Smin) down to 70 mV/decade was achieved by employing an InGaP top barrier layer and a cap doping of ∼2 × 10 19 cm −3 was obtained with a Si-Te co-doping technique. An effective mobility (μ eff ) of ∼4900 cm 2 /Vs at sheet electron density (N) of 3 × 10 12 cm −2 was achieved which is record among InxGa 1 -xAs (x < 0.53) MOSFETs on Si substrates. In addition, current-gain cut-off frequency f T ) of ∼60 GHz was extracted for 150 nm channel length MOSHEMTs.
    We studied a high indium content (0.8) InGaN based solar cell design where the active InGaN layer is sandwiched between a GaN cap layer and a GaN spacer layer. The incorporation of the sacrificial cap layer allows for the etching of the front surface without removing the active InGaN resulting in a 50% enhancement of the short-circuit current density for a 15 nm-thick InGaN layer.
    Active layer
    Citations (3)
    We performed ab initio density functional theory simulations of $\frac{1}{2}\ensuremath{\langle}111\ensuremath{\rangle}$ interstitial dislocation loops, closed and open vacancy loops, $\ensuremath{\langle}100\ensuremath{\rangle}$ interstitial loops, and voids in tungsten, using simulation cells involving from 2000 to 2700 atoms. The size of the loops transcends the microscopic scale and reaches the mesoscopic scale where asymptotic elasticity treatment applies. Comparing the formation energies of dislocation vacancy loops and voids, we conclude that a void remains the most energetically favorable vacancy defect over the entire range of sizes investigated here. A closed $\frac{1}{2}\ensuremath{\langle}111\ensuremath{\rangle}$ vacancy loop is more stable than an open loop if the number of vacancies in the loop is greater than $\ensuremath{\sim}45$, corresponding to the diameter of a loop of approximately 1.8 nm. We have also computed elastic dipole tensors and relaxation volumes of loops and voids, representing the source terms in continuum models for radiation induced stresses and strains in the material. A detailed analysis of metastable configurations of closed and open vacancy loops performed using molecular statics simulations shows that vacancy loop configurations are not unique, and significant fluctuations of defect structures may occur in the course of microstructural evolution under irradiation.
    Mesoscopic physics
    Void (composites)
    Metastability
    Бұл зерттеужұмысындaКaно моделітурaлы жәнеоғaн қaтыстытолықмәліметберілгенжәнеуниверситетстуденттерінебaғыттaлғaн қолдaнбaлы (кейстік)зерттеужүргізілген.АхметЯссaуи университетініңстуденттеріүшін Кaно моделіқолдaнылғaн, олaрдың жоғaры білімберусaпaсынa қоятынмaңыздытaлaптaры, яғнисaпaлық қaжеттіліктері,олaрдың мaңыздылығытурaлы жәнесaпaлық қaжеттіліктерінеқaтыстыөз университетінқaлaй бaғaлaйтындығытурaлы сұрaқтaр қойылғaн. Осы зерттеудіңмaқсaты АхметЯсaуи университетіндетуризмменеджментіжәнеқaржы бaкaлaвриaт бaғдaрлaмaлaрыныңсaпaсынa қaтыстыстуденттердіңқaжеттіліктерінaнықтaу, студенттердіңқaнaғaттaну, қaнaғaттaнбaу дәрежелерінбелгілеу,білімберусaпaсын aнықтaу мен жетілдіружолдaрын тaлдaу болыптaбылaды. Осы мaқсaтқaжетуүшін, ең aлдыменКaно сaуaлнaмaсы түзіліп,116 студенткеқолдaнылдыжәнебілімберугежәнеоның сaпaсынa қaтыстыстуденттердіңтaлaптaры мен қaжеттіліктерітоптықжұмыстaрaрқылыaнықтaлды. Екіншіден,бұл aнықтaлғaн тaлaптaр мен қaжеттіліктерКaно бaғaлaу кестесіменжіктелді.Осылaйшa, сaпa тaлaптaры төрт сaнaтқa бөлінді:болуытиіс, бір өлшемді,тaртымдыжәнебейтaрaп.Соңындa,қaнaғaттaну мен қaнaғaттaнбaудың мәндеріесептелдіжәнестуденттердіңқaнaғaттaну мен қaнaғaттaнбaу деңгейлерінжоғaрылaту мен төмендетудеосытaлaптaр мен қaжеттіліктердіңрөліaйқын aнықтaлды.Түйінсөздер:сaпa, сaпaлық қaжеттіліктер,білімберусaпaсы, Кaно моделі.
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    Herein, we reported the effects of the geometric morphology of the sidewall on the extraction efficiency of GaN-based light-emitting diodes (LEDs). We performed numerical analysis based on the ray-tracing method. We found that the extraction efficiency of the LEDs increased with the texturing of the sidewall. The light output intensity of the LEDs (at an injection current of 100 mA) increased by 13.8% after sidewall texturing. These results confirmed that the geometric morphology of the sidewall plays an important role in improving the extraction efficiency of LEDs.
    Citations (3)
    Using single-walled carbon nanotubes (SWCNTs) as nanomasks on an undoped GaN template, a significant biaxial stress relaxation was achieved in the subsequently-grown Si-doped n-GaN layer. Enhanced near band edge (NBE) emission intensity, similar free carrier concentrations, and the reduced peak width of the asymmetric (102) crystallographic plane all confirmed the suppression of threading dislocations due to the nanoepitaxial growth process. Temperature-dependent photoluminescence (PL) revealed improved internal quantum efficiency (IQE) of InGaN/GaN multi-quantum wells (MQWs) grown on this n-GaN layer. Furthermore, enhanced light output power and a remarkable reduction in efficiency droop were observed for the blue light-emitting diodes (LEDs), especially at higher injection currents. Our results emphasize the strong potential for SWCNTs as nanomasks in the heteroepitaxy of GaN-based devices without the exploitation of complicated lithography or etching processes.
    Quantum Efficiency