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Low-pressure metalorganic chemical vapor deposition was used to create AlGaInP/GaInP visible strained quantum well lasers. A visible laser diode developed through AlInP cladding layer features a threshold current of 30 mA and an output of at least 32 mW under continuous wave operation at room temperature. Test results indicate the possibility of reducing transverse beam divergence at low threshold current.

GaN metal-semiconductor-metal (MSM) ultraviolet photodetectors with titanium tungsten (TiW) transparent electrodes were fabricated and characterized. It was found that the 10-nm-thick TiW film deposited with a 300-W RF power can still provide a reasonably high transmittance of 75.1% at 300 nm, a low resistivity of 1.7 × 10-3 Ω·cm and an effective Schottky barrier height of 0.773 eV on u-CaN. We also achieved a peak responsivity of 0.192 A/W and a quantum efficiency of 66.4% from the GaN ultraviolet MSM photodetector with TiW electrodes. With a 3-V applied bias, it was found that minimum noise equivalent power and maximum D* of our detector were 1.987 × 10-10 W and 6.365 × 109 cmHz0.5W-1, respectively. [ABSTRACT FROM AUTHOR]

Nitride-based flip-chip (FC) light-emitting diodes (LEDs) emitting at 465 nm with Ni transparent ohmic contact layers and Ag reflective mirrors were fabricated. With an incident light wavelength of 465 nm, it was found that transmittance of normalized 300 °C rapid thermal annealed (RTA) Ni(2.5 nm) was 93% while normalized reflectance of 300 °C RTA Ni(2.5 nm)/Ag(200 nm) was 92%. It was also found that 300 °C RTA Ni(2.5 nm) formed good ohmic contact on n+ short-period-superlattice structure with specific contact resistance of 7.8 × 10-4 Ω·cm². With 20-mA current injection, it was found that forward voltage and output power were 3.15 V and 16.2 mW for FC LED with 300 °C RTA Ni(2.5 nm)/Ag(200 nm). Furthermore, it was found that reliabilities of FC LEDs were good. [ABSTRACT FROM AUTHOR]

We have prepared bulk p-AIInGaN layers and light-emitting diodes (LEDs) with p-AIInGaN surface layers by metal-organic chemical vapor deposition. By properly control the TMAI and TMIn flow rates, we could match the lattice constant of p-AIInGaN to that of GaN. It was found that surface of the LED with p-AIInGaN layer was rough with a high density of hexagonal pits. Although the forward voltage of the LED with p-AIInGaN layer was slightly larger, it was found that we can enhance the output power by 54% by using p-AIInGaN surface layer. [ABSTRACT FROM AUTHOR]

Nitride-based light emitting diodes (LEDs) separately prepared with a conventional single low-temperature (LT) GaN nucleation layer and multiple CaN-SiN nucleation layers were both prepared. It was found that we could reduce defect density and thus improve crystal quality of the GaN-based LEDs by using multiple GaN-SiN nucleation layers. With a 20-V applied reverse bias, it was found that the reverse leakage currents measured from the LED with a single LT GaN nucleation layer and the one with 10-pair GaN-SiN nucleation layers were 1.5 × 10-4 and 2.5 × 10-6 A, respectively. It was also determined that we could use the multiple GaN-SiN nucleation layers to enhance the output intensity of near ultraviolet (UV) LEDs and to improve the reliability of nitride-based LEDs. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) (260 nm) and Ni (5 nm)/Au (10 nm) films were deposited onto glass substrates, p-GaN layers, n[SUP+] -InGaN/GaN short-period-superlattice (SPS), n[SUP++]-SPS and ni. tride-based green light-emitting diodes (LEDs). It was found that ITO could provide us an extremely high transparency (i.e., 95% at 520 nm). It was also found that the 1.03 × 10[SUP-3] Ωcm[SUP2] specific contact resistance of ITO on n[SUP++]-SPS was reasonably small. Although forward voltage of the LED with ITO on n[SUP++]-SPS upper contact was slightly higher than that of the LED with Ni/Au on n[SUP++]-SPS upper contact, 20 mA output power and external quantum efficiency of the green LED with ITO on n[SUP++]-SPS upper contact could reach 4.98 mW and 8.2%, respectively, which were much larger than those observed from the green LED with Ni/Au on n[SUP++]-SPS upper contact. The reliability of ITO on n[SUP++]-SPS upper contact was also found to be reasonably good. [ABSTRACT FROM AUTHOR]

Deals with a study of optical and electrical properties of nitride-based p-down light emitting diodes. Experimental details; Results and discussion.

We report the homoepitaxial growth of ZnSe layers on ZnSe substrates by molecular beam epitaxy (MBE). It was found that we can only observe an extremely strong ZnSe (004) x-ray peak with a full-width-at-half-maximum of 21.5 arcsec, which is much smaller than that observed from ZnSe grown on GaAs substrates. Photoluminescence and Hall measurement also indicate that the quality of our homoepitaxial ZnSe layers is good. ZnSe-based homoepitaxial metal-semiconductor-metal photodetectors with transparent indium-tin-oxide (ITO) contact electrodes were also fabricated. It was found that although ITO transparent contact electrodes can result in large photon absorption and large photocurrents, the low Schottky barrier height between ITO and homoepitaxial ZnSe would also result in relatively large dark currents. With an incident wavelength of 450 nm and a 1-V applied bias, it was found that the maximum responsivity is about 0.13 A/W, which corresponds to a quantum efficiency of 35%. Furthermore, it was found that the detector responsivity drops by more than two orders of magnitude across the cutoff region. [ABSTRACT FROM AUTHOR]

Nitride-bass light-emitting diodes (LEDs) with Mg-doped In[sub0.23]Ga[sub0.77]N capping layers were successfully fabricated. Compared to Mg-doped GaN layers, it was found that we could achieve a much larger hole concentration from Mg-doped In[sub0.23]Ga[sub0.77]N layers. It was also found that we could reduce the 20 mA operation voltage from 3.78 to 3.37 V by introducing a 5-nm-thick In[sub0.23]Ga[sub0.77]N layer on top of the p-GaN layer. Furthermore, it was found that output intensity of LEDs with In[sub0.23]Ga[sub0.77]N capping layer was much larger, particularly at elevated temperatures. [ABSTRACT FROM AUTHOR]