III-V Semiconductors Research Papers - Academia.edu (original) (raw)

A set of heavily doped Al0.48In0.52As samples grown by molecular beam epitaxy on InP (Fe) substrates was investigated using the photoreflectance (PR) technique. The spectra at 300 K are characterized by a transition in the vicinity of the... more

A set of heavily doped Al0.48In0.52As samples grown by molecular beam epitaxy on InP (Fe) substrates was investigated using the photoreflectance (PR) technique. The spectra at 300 K are characterized by a transition in the vicinity of the InP energy gap, followed by strongly damped Franz-Keldysh oscillations (FKOs) which do not appear when the spectra are obtained at 77 K. The builtin electric field estimated from FKOs shows a small doping dependence but is substantially affected by the inclusion of a thin layer of AlxGayIn1-x-yAs (x≡0.22) at the interface between InP (Fe) and AlInAs:Si. In order to explain these results, a model based on the discontinuity of the energy bands in the InP/AlInAs and InP/AlGaInAs/AlInAs systems and also on the matching of the Fermi levels between the different materials is suggested.

Two twelve-channel arrays based on surface-etched slot gratings, one with nonuniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm,... more

Two twelve-channel arrays based on surface-etched slot gratings, one with nonuniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm, with a side-mode suppression ratio (SMSR) > 40 dB over much of this range and output power greater than 20 mW, was obtained for the array with non-uniform slots over a temperature range of 15°C-60°C. The introduction of multiple slot periods, chosen such that there is minimal overlap among the side reflection peaks, is employed to suppress modes lasing one free spectral range (FSR) from the intended wavelength. The tuning range of the array with uniformly spaced slots, on the other hand, was found to be discontinuous due to mode-hopping to modes one FSR away from the intended lasing mode which are not adequately suppressed. Spectral linewidth was found to vary across devices with the lowest measured linewidths in the range of 2 MHz to 4 MHz.

III–V compounds containing heavy Bi anion are distinguished from remaining III–V family in terms of their narrower electronic energy gap and potential application for infrared/near infra devices. In the present work, modeling of X–Bi (X =... more

III–V compounds containing heavy Bi anion are distinguished from remaining III–V family in terms of their narrower electronic energy gap and potential application for infrared/near infra devices. In the present work, modeling of X–Bi (X = B, Al, Ga and In) compounds and the investigations pertaining to their physical properties were carried out using density functional theory (DFT) based full-potential linearized augmented plane wave plus local orbital, FP-L(APW + lo) approach within various functional of the exchange correlation potentials. The calculated total energies of X–Bi in various geometries reveal that zinc blende phase is the stable ground state structure of BBi, AlBi and GaBi. However, InBi adapts PbO phase at ground state. It was also found that BBi exhibit an electronic structure with an indirect energy gap. However, AlBi, GaBi and InBi are semi-metallic with a narrower or zero band gap. The calculation of the optical properties show that among X–Bi compounds, BBi was found to exhibit higher absorption coefficient values, lower reflectivity and refractive index, enlightening their potential for infrared/near infra devices and other optoelectronic applications as well.

—-Gallium nitride (GaN) based metal-oxide semiconductor field-effect transistors (MOSFETs) are promising for switching device applications. The doping of n-and players is varied to evaluate the figure of merits of proposed devices with a... more

—-Gallium nitride (GaN) based metal-oxide semiconductor field-effect transistors (MOSFETs) are promising for switching device applications. The doping of n-and players is varied to evaluate the figure of merits of proposed devices with a gate length of 10 nm. Devices are switched from OFF-state (gate voltage, VGS = 0 V) to ON-state (VGS = 1 V) for a fixed drain voltage, VDS = 0.75 V. The device with channel doping of 1×1016 cm-3 and source/drain (S/D) of 1×1020 cm-3 shows good device performance due to better control of gate over channel. The ON-current (ION), OFF-current (IOFF), subthreshold swing (SS), drain induce barrier lowering (DIBL), and delay time are found to be 6.85 mA/μm, 5.15×10-7 A/μm, 87.8 mV/decade, and 100.5 mV/V, 0.035 ps, respectively. These results indicate that GaN-based MOSFETs are very suitable for the logic switching application in nanoscale regime.

Cartografía territorial y caracterización de los suelos tipo del municipio de Tauste. Leticia Gaspar Ferrer, Leticia Palazón Tabuenca, Laura Quijano Gaudes, Ana Navas Izquierdo. Tauste en el ocaso del Valle del Ebro musulmán... more

Cartografía territorial y caracterización de los suelos tipo del municipio de Tauste. Leticia Gaspar Ferrer, Leticia Palazón Tabuenca, Laura Quijano Gaudes, Ana Navas Izquierdo.
Tauste en el ocaso del Valle del Ebro musulmán (1080- 1125). Esplendor y declive de una civilización perdida. Carlos Laliena Corbera
Roncesvalles y el reino de Aragón: El ejemplo de Tauste y la comarca de Cinco Villas. Fermín Miranda García.
Al servicio del Tercer Reich. Taustanos en la División Azul y el Frente del Este. Luis Antonio Palacio Pilacés.

In this paper one can find a detailed description of the research performed by author during his stay at IMEC (Belgium). It deals with the experimental verification of the highly coherent electron spin transport across ferromagnetic metal... more

In this paper one can find a detailed description of the research performed by author during his stay at IMEC (Belgium). It deals with the experimental verification of the highly coherent electron spin transport across ferromagnetic metal / semiconductor interface at low and room temperatures.

Ultra-compact, widely-tunable and low-power InP-based four-section couple-cavity lasers are designed and analyzed. Two Fabry-Pérot cavities of unequal lengths, each containing an amplifier and a phase-tuning section are coupled together... more

Ultra-compact, widely-tunable and low-power InP-based four-section couple-cavity lasers are designed and analyzed. Two Fabry-Pérot cavities of unequal lengths, each containing an amplifier and a phase-tuning section are coupled together through low-loss Bragg grating. The theoretical analysis of such multisection lasers starts with calculating the poles of a linear transfer function of the entire resonator in order to obtain resonant wavelengths and wavelength dependent threshold gains. The differential quantum efficiency and the power-current characteristics are then calculated to evaluate the laser performance. The effectiveness of the design procedure is verified by the experimental and proof-of-principle demonstration using simplified three-section lasers. Devices exhibit single-mode operation with a side-mode suppression ratio of over 24 dB and tuning range of 11.2 nm. These telecom-suitable lasers can be used as on-chip local oscillators in low-power integrated optical coherent receivers.

Two of the key challenges in the realisation of focal plane arrays based on type-II InAs/GaSb superlattices (T2SL) are the difficulty in achieving a good sidewall profile and the increased dominance of surface leakage current as the... more

Two of the key challenges in the realisation of focal plane arrays based on type-II InAs/GaSb superlattices (T2SL) are the difficulty in achieving a good sidewall profile and the increased dominance of surface leakage current as the device dimensions shrink. We report the electrical and morphological results of test pixels for mid-wave infrared T2SL photodiodes etched using a Cl2/Ar based inductively coupled plasma reactive ion etching (ICP-RIE) process and passivated using SU-8 epoxy photoresist. The etch rate and sidewall surface morphology of GaSb, InAs, and InAs/GaSb T2SL materials are compared after dry etching under the same conditions, leading to the determination of an optimal etch rate. The effect of surface treatment using selected wet chemical etchants before passivation on the surface leakage current is presented. Limitations of the dry etching recipe and further improvement of the sidewall verticality and smoothness are also discussed. Good sidewall profiles and bulk-limited dark currents are demonstrated for T2SL photodiodes etched to depths between 1.5 and 3.5 μm with a pitch size down to 12 μm.

Carrier concentration profiles of two-dimensional electron gases are investigated in wurtzite, Ga-face and N-face heterostructures used for the fabrication of field effect transistors. Analysis of the measured electron distributions in... more

Carrier concentration profiles of two-dimensional electron gases are investigated in wurtzite, Ga-face and N-face heterostructures used for the fabrication of field effect transistors. Analysis of the measured electron distributions in heterostructures with AlGaN barrier layers of ...

In this paper we discuss the effect of dissipated power on the characteristic time of noise spectra transformation investigated in wide-bandgap AlGaN/GaN transistor structures with long channels. It is found that the characteristic time... more

In this paper we discuss the effect of dissipated power on the characteristic time of noise spectra transformation investigated in wide-bandgap AlGaN/GaN transistor structures with long channels. It is found that the characteristic time as a function of temperature demonstrates an exponential dependence with definite activation energy. Obtained results are explained based on the developed model of non-equilibrium fluctuations of the sample resistance. These fluctuations cause a local overheating due to local change of resistance. In the long channels these fluctuations may create overheating regions with two different self-heating temperatures, leading to different activation dependences, observed in the experiment.

This paper reports on the results of the experimental and numerical investigation into the self-heating effect in AlGaN/GaN heterostructures grown on sapphire and SiC substrates. It shows that temperature increase has an opposite... more

This paper reports on the results of the experimental and numerical investigation into the self-heating effect in AlGaN/GaN heterostructures grown on sapphire and SiC substrates. It shows that temperature increase has an opposite dependence on the buffer thickness for sapphire and SiC substrates. Noise spectroscopy is also used to monitor the self-heating effect. Moreover, it is shown that the room-temperature spectra can be used to determine the activation energy of the traps. An irreversible improvement in mobility and quantum scattering time is registered after the irradiation of AlGaN/GaN heterostructures at a total dose of 1 × 106 rad of 60Co gamma rays.

Strain relaxation in III–V semiconductor (0 0 1) epitaxial strained layers is considered with particular reference to the InGaAs/GaAS system. Possible mechanisms of relaxation are briefly reviewed. It is pointed out that relaxation is,... more

Strain relaxation in III–V semiconductor (0 0 1) epitaxial strained layers is considered with particular reference to the InGaAs/GaAS system. Possible mechanisms of relaxation are briefly reviewed. It is pointed out that relaxation is, and never can be, complete and that results relating to the extent of relaxation of thick layers, and the asymmetry of such relaxation in the two 〈1 1 0〉 should be interpreted with caution. Any asymmetry introduced by the use of vicinal substrates is less than the scatter among experimental measurements of relaxation.