Refine my results

Specific Collection

Language

Université de Neuchâtel

Near infrared intersubband absorption and photovoltaic detection in GaN/AIN multi quantum well structures

Baumann, Esther ; Hofstetter, Daniel (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2007 ; Th.1956.

Due to the large conduction band offset of nearly 2 eV between GaN and AlN, group III nitride semiconductor heterostructures are of great interest for optoelectronics based on intersubband transitions (ISBTs). These properties allow the extension of the ISBT wavelength range into the near infrared. In this work near infrared ISBTs in GaN/AlN heterostructures were investigated for samples grown by...

Université de Neuchâtel

Near infrared absorption and room temperature photovoltaic response in AlN/GaN superlattices grown by metal-organic vapor-phase epitaxy

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Golka, Sebastian ; Schrenk, W. ; Strasser, Gottfried ; Kirste, Lutz

In: Applied Physics Letters, 2006, vol. 89, no. 041106, p. 1-3

We report on intersubband absorption of near infrared radiation in AlN/GaN superlattice structures grown by metal-organic vapor-phase epitaxy. A good correlation between well thickness and absorption peak energy was obtained. One sample shows a photovoltaic signal which overlaps well with the corresponding absorption curve at around 1.5 µm (830 meV), a common wavelength in optical fiber...

Université de Neuchâtel

Electrically adjustable intersubband absorption of a GaN/AlN superlattice grown on a transistorlike structure

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Leconte, Sylvain ; Guillot, Fabien ; Bellet-Amalric, Edith ; Monroy, Eva

In: Applied Physics Letters, 2006, vol. 89, no. 101121, p. 1-3

The authors report on electromodulated intersubband (ISB) absorption experiments on AlN/GaN superlattices (SLs) grown on a transistorlike structure. A sample containing five SL periods shows two distinct absorption peaks related to ISB transitions in the SL and in the two dimensional electron gas located at the interface of the lowest SL barrier and the underlying GaN buffer. The ratio of those...

Université de Neuchâtel

Tunneling effects and intersubband absorption in AlN/GaN superlattices

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Wu, H. ; Schaff, W. J. ; Eastman, L. F. ; Kirste, Lutz

In: Applied Physics Letters, 2006, vol. 86, no. 032110, p. 1-3

We report on intersubband absorption and photovoltage measurements on regular GaN/AlN-based superlattice structures. For barrier thicknesses larger than about 25 Å, the optical intersubband absorption peaks at a considerably smaller energy than the photovoltage spectrum. A simple model taking into account the oscillator strength of the involved transitions and the corresponding tunneling...

Université de Neuchâtel

Intersubband photoconductivity at 1.6 µm using a strain-compensated AlN/GaN superlattice

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Lu, H. ; Chen, X. ; Schaff, William J. ; Eastman, L. F. ; Golka, Sebastian ; Schrenk, W. ; Strasser, Gottfried

In: Applied Physics Letters, 2005, vol. 87, no. 191102, p. 1-3

We report on intersubband absorption, photovoltaic, and photoconductive detection of near-infrared radiation in regular AlN/GaN superlattice structures. Photoconductive detection was achieved up to temperatures of 120 K. Simulation of the transition energies using a self-consistent Schrödinger-Poisson equation solver for our specific well width is in good agreement with the measurements. For a...

Université de Neuchâtel

Resonant tunnelling and intersubband absorption in AlN - GaN superlattices

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Wu, Hong ; Schaff, William J. ; Eastman, Lester F. ; Kirste, Lutz

In: Physica status solidi (c), 2005, vol. 2, no. 3, p. 1014-1018

We report on intersubband absorption and photovoltage measurements on regular GaN/AlN-based superlattice structures at 1.55 µm. For high barriers, the photovoltage peaks at a higher energy than the absorbance spectrum due to the decrease of the tunnelling probability. The observed photovoltage is thus the macroscopic manifestation that the 2-dimensional electron gas at the top of the...

Université de Neuchâtel

GaN/AlN electro-optical modulator prototype at telecommunication wavelengths

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Guillot, Fabien ; Leconte, Sylvain ; Bellet-Amalric, Edith ; Monroy, Eva

In: Physica status solidi (c), 2007, vol. 4, no. 5, p. 1621-1624

We report on a prototype electro-optical modulator at telecommunication wavelength based on intersubband (ISB) transitions in a short-period GaN/AlN superlattice (SL). The device has a vertical architecture resembling a nitride-based high-electron mobility transistor, whose barrier layer has been replaced by a 5 period SL. By applying an electrical field, we were able to influence the...

Université de Neuchâtel

Short wavelength (4 µm) quantum cascade detector based on strain compensated InGaAs/InAlAs

Giorgetta, Fabrizio R. ; Baumann, Esther ; Théron, Ricardo ; Pellaton, M. L. ; Hofstetter, Daniel ; Fischer, M. ; Faist, Jérôme

In: Applied Physics Letters, 2008, vol. 92, no. 121101, p. 1-3

We report on a quantum cascade detector based on nearly strain compensated InGaAs/InAlAs pseudomorphically grown on InP substrate and detecting light at short wavelengths around 4 µm. The background limited infrared performance (BLIP) condition is met at a temperature of 108 K with a high detectivity of D*BLIP =1.2×1011 Jones.

Université de Neuchâtel

16.5 µm quantum cascade detector using miniband transport

Giorgetta, Fabrizio R. ; Baumann, Esther ; Graf, Marcel ; Ajili, Lassaad ; Hoyler, Nicolas ; Marcella Giovannini ; Faist, Jérôme ; Hofstetter, Daniel ; Krötz, Peter ; Sonnabend, Guido

In: Applied Physics Letters, 2007, vol. 90, no. 231111, p. 1-3

The authors report on an InP based photovoltaic quantum cascade detector operating at 16.5 µm and using miniband-based vertical transport. This concept allowed the construction of a longitudinal optical phonon extraction stair with two rungs without touching on a high device resistance. At 10 K, they observed a responsivity of 1.72 mA/W and a Johnson noise limited detectivity of 2.2×109...