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The HF gas detection sensitivity of GaSb-based distributed feedback lasers was studied in order to evaluate the potential use of operating temperature to control the laser output power in field applications. Measurements were made in the 2f wavelength modulation spectroscopy mode to monitor a prominent HF absorption feature at 2396 nm. An Allan variance analysis indicates that the best sensitivity is obtained when a larger thermoelectric current is applied to maintain temperature control by actively heating or cooling the laser. The reduced detection sensitivity for a setpoint near the ambient laser operating temperature is similar to that obtained without active temperature control. [ABSTRACT FROM AUTHOR]

Type-I interband lasers on GaSb were grown by molecular beam epitaxy using 16 nm InGaAsSb compressively-strained quantum wells (QWs) with 30 nm AlInGaAsSb quinary barriers for improved hole confinement. The 3QW active regions were embedded in standard AlGaAsSb waveguides to limit the thickness of quinary material owing to its low growth temperature requirements. In continuous-wave operation, a typical ridge waveguide laser (width 10 µm, length 1214 µm) produced 6 mW total output power at 20°C with a threshold current of 140 mA. The temperature sensitivity of the devices remains a challenge, as evidenced by the dramatically improved performance at 0°C (16 mW total output power, threshold current 74 mA). [ABSTRACT FROM AUTHOR]

AlGaN/GaN heterostructure field effect transistors (HFETs) fabricated from maskless selectively grown mesas by ammonia molecular beam epitaxy on Si(111) substrates are demonstrated. With 0.8 µm gate length, the devices exhibited maximum drain current and transconductance of 425 mA/mm and 140 mS/mm, respectively. Values of fT and fMAX of 8 and 19 GHz, respectively, were obtained from RF measurements. A 50 nm-thick SiNx passivation layer was found to be very effective in mitigating the current collapse. [ABSTRACT FROM AUTHOR]