A monolithically integrated tunable laser and quantum-well phase modulator is demonstrated. Phase efficiency under forward bias is improved >20dB at low frequencies compared with reverse bias. Bandwidths >30 GHz are demonstrated in frequency modulation measurements. 2006 Optical Society of America OCIS codes: (230 4110) Modulators; (230 5590) Quantum Well Devices This research was supported by...

ardy and littlewood conjectured that every large integer $n$ that is not a square is the sum of a prime and a square. they believed that the number $mathcal{r}(n)$ of such representations for $n = p+m^2$ is asymptotically given by begin{equation*} mathcal{r}(n) sim frac{sqrt{n}}{log n}prod_{p=3}^{infty}left(1-frac{1}{p-1}left(frac{n}{p}right)right), end{equation*} where $p$ is a prime, $m$ is a...

Pt/AlGaN/AlN/GaN high electron mobility transistors (HEMT) were fabricated and characterized for hydrogen sensing. Pt and Ti/Al/Ni/Au metals were evaporated to form the Schottky contact and the ohmic contact, respectively. The sensors can be operated in either the field effect transistor (FET) mode or the Schottky diode mode. Current changes and time dependence of the sensors under the FET and ...

The dependence of band-to-band tunneling in p+-Si1−xGex /n+-Si1−xGex homojunctions on Ge fraction and electric field is investigated in the range 2–3×108 V/m. Negative differential resistance (NDR) in forward bias is observed for each device with the highest peak tunneling-current density of 8.2 kA/cm2 without any postannealing step. Reverse-biased band-to-band tunneling, as relevant for tunnel...

Trapping effects on two AlGaN/GaN Schottky diodes with a different composition of the AlGaN barrier layer were analyzed by current transient spectroscopy. The current transients were measured at a constant bias and at six different temperatures between 25 and 150 ̋C. Obtained data were fitted by only three superimposed exponentials, and good agreement between the experimental and fitted data wa...