Deep UV photoluminescence and Hall-effect measurements were employed to characterize Mg-doped AlN grown by metal organic chemical vapor deposition. A strong correlation between the optical and electrical properties was identified and utilized for material and p-type conductivity optimization. An impurity emission peak at 4.7eV, attributed to the transition of electrons bound to triply charged nitrogen vacancies to neutral magnesium impurities, was observed in highly resistive epilayers. Improved conductivity was obtained by suppressing the intensity of the 4.7eV emission line. Mg-doped AlN epilayers with improved conductivities predominantly emit the acceptor-bound exciton transition at 5.94eV. From the Hall-effect measurements performed at elevated temperatures, the activation energy of Mg in AlN was measured to be about 0.5eV, which is consistent with the value obtained from previous optical measurements. Energy levels of nitrogen vacancies and Mg acceptors in Mg-doped AlN have been constructed.

The authors report on the synthesis of Er-doped GaN epilayers by in situ doping by metal-organic chemical vapor deposition (MOCVD). The optical and electrical properties of the Er-doped GaN epilayers were studied by photoluminescence (PL) spectroscopy and van der Pauw–Hall method. Both above and below band gap excitation results in a sharp PL emission peak at 1.54μm. In contrary to other growth methods, MOCVD grown Er-doped GaN epilayers exhibit virtually no visible emission lines. A small thermal quenching effect, with only a 20% decrease in the integrated intensity of the 1.54μm PL emission, occurred between 10 and 300K. It was found that Er incorporation has very little effect on the electrical conductivity of the GaN epilayers and Er-doped layers retain similar electrical properties as those of undoped GaN.

The authors report on the excitation dynamics of the photoluminescence ͑PL͒ emission of Er doped GaN thin films synthesized by metal organic chemical vapor deposition. Using the frequency tripled output from a Ti:sapphire laser, the authors obtained PL spectra covering the ultraviolet ͑UV͒ to the infrared regions. In the UV, a dominant band edge emission at 3.23 eV was observed at room temperature; this is redshifted by 0.19 eV from the band edge emission of undoped GaN. An activation energy of 191 meV was obtained from the thermal quenching of the integrated intensity of the 1.54 m emission line. This value coincides with the redshift of the band edge emission and is assigned to the Er Ga -V N complex level.

We present here on the growth, fabrication and electroluminescence ͑EL͒ characteristics of light emitting diodes ͑LEDs͒ based on Er-doped InGaN active layers. The p-in structures were grown using metal organic chemical vapor deposition and processed into 300ϫ 300 m 2 mesa devices. The LEDs exhibit strong emissions at 1.0 and 1.54 m, due to Er intra-4f transitions, under forward bias conditions. The emitted EL intensity increases with applied input current without exhibiting saturation up to 70 mA. The integrated power over the near infrared emission, measured at room temperature from the top of a bare chip, is about 2 W. The results represent a significant advance in the development of current injected, chip-scale emitters and waveguide amplifiers based on Er doped semiconductors.

Strip optical waveguides based on erbium ͑Er͒-doped AlGaN/GaN:Er/AlGaN heterostructures have been fabricated and characterized in the optical communication wavelength window near 1.54 m. The propagation loss of these waveguide amplifiers have been measured at 1.54 m and found to be 3.5 cm −1. Moreover, the optical amplification properties of the waveguides were measured using a signal input at 1.54 m and a broadband GaN light-emitting diode at 365 nm as pump source. A relative signal enhancement of ϳ8 cm −1 was observed. The implications of such devices in photonic integrated circuits for optical communications are discussed.