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Waveguide Design for Long Wavelength InGaN Based Laser Diodes

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Muzioł G., Turski H., Siekacz M., Sawicka M., Wolny P., Cheze C., Cywiński G., Perlin P., Skierbiszewski C.

Acta Physica Polonica A

2012

vol. 122

issue 6

1031-1033

One-dimensional optical waveguide calculations were performed to study the dependence of waveguide design on confinement factor (Γp) and optical losses (α_i) of nitride laser diodes for emission wavelength ranging from 405 nm to 520 nm. We found that the conventional waveguide design containing GaN waveguide and AlGaN cladding layers known from violet laser diode does not support sufficient confinement of the optical mode for long wavelength devices (λ > 450 nm). We proposed a new design consisting of a thick InGaN waveguide which enhances the confinement. We compared the theoretical predictions with laser diodes grown by plasma assisted molecular beam epitaxy.

Electrostatic Gates for GaN/AlGaN Quantum Point Contacts

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Czapkiewicz M., Cywiński G., Dybko K., Siekacz M., Wolny P., Gierałtowska S., Guziewicz E., Skierbiszewski C., Wróbel J.

Acta Physica Polonica A

2012

vol. 122

issue 6

1026-1028

We report on AlGaN/GaN quantum point contacts fabricated by using e-beam lithography and dry ion etching. The tunable nano-constrictions are defined by the integration of side and top gates in a single device. In this configuration, the planar gates are located on the both sides of a quantum channel and the metallic top gates, which cover the active region, are separated from the substrate by an insulating and passivating layers of HfO_2 or Al_2O_3/HfO_2 composite. The properties of devices have been tested at T = 4.2 K. For side gates we have obtained a very small surface leakage current I_g< 10^{-11} A at gate voltages |V_g| < 2 V, however, it is not enough to close the quantum channel. With top gates we have been able to reach the pinch-off voltage at V_g = - 3.5 V at a cost of I_g ≈ 10^{-6} A, which has been identified as a bulk leakage current.

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2 Acta Physica Polonica A

2 2012

2 Cywiński G.

2 Siekacz M.

2 Skierbiszewski C.

2 Wolny P.

1 Cheze C.

1 Czapkiewicz M.

1 Dybko K.

1 Gierałtowska S.

1 Guziewicz E.

1 Muzioł G.

1 Perlin P.

1 Sawicka M.

1 Turski H.

1 Wróbel J.

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Waveguide Design for Long Wavelength InGaN Based Laser Diodes

Electrostatic Gates for GaN/AlGaN Quantum Point Contacts