K. Y. Cheng

Liquid‐phase‐epitaxial growth of In0.49Ga0.51P on (100) GaAs by a supercooling method

In1−xGaxP epitaxial layers were grown on (100) GaAs substrates by liquid‐phase epitaxy using supercooling technique. The lattice mismatch normal to the wafer surface between In1−xGaxP layer and GaAs substrate varies linearly with the supercooled temperature of the growth solution. The composition‐pulling phenomenon was not observed in this study. The growth rate, the intensity, and the full width at half maximum of the photoluminescent spectrum are also dependent on the supercooling temperature. It is shown that the narrowest full widths at half maximum of photoluminescent peak are 10.6 and 35 meV at 14 and 300 K, respectively, when ΔT is 6u2009°C, and the strongest intensity is occurred at ΔT=12–18u2009°C. Carrier concentrations of undoped epitaxial layers are in the range of 1016 cm−3 measured by capacitance‐voltage method at 300 K and Hall method at 77 and 300 K. The optimum growth condition was then determined.

Electrical and optical properties of high purity In0.5Ga0.5P grown on GaAs by liquid phase epitaxy

Abstract The growth of high purity In 0.5 Ga 0.5 P epitaxial layers was carried out by liquid phase epitaxy with a supersaturation temperature of 6° C. The lattice mismatch between the InGaP layer and the GaAs substrate was 0.10% measured by X-ray diffraction. The bandgap and the quality of the epitaxial layers were determined by photoluminescence. The narrowest full width at half maximum of the photoluminescent spectra was 35.0 and 10.6 meV at 300 and 14 K, respectively. Hall and capacitance-coltage measurements show that a net carrier concentration of 3 × 10 15 cm −3 has been achieved, which is by one or two orders of magnitude lower than those previously reported. Forward bias current-voltage measurement of a Au-In 0.5 Ga 0.5 P Schottky diode shows that the ideality factor n is calculated to be 1.08 and the barrier height φ n is 0.95 eV. This value is rather close to that of 1.02 eV obtained by capacitance-voltage measurements. Deep level traps in the In 0.5 Ga 0.5 P epitaxial layer were studied by deep level transient spectroscopy. The only thermal activated energy level is located at E c - 0.39 eV and the electron trap concentration is below 2 × 10 14 cm −3 .

Tellurium and zinc doping in In0.5Ga0.5P grown by liquid‐phase epitaxy

In0.5Ga0.5P epitaxial layers doped with Te and Zn were grown on (100) GaAs substrates by liquid‐phase epitaxy using a supercooling method. The lattice mismatch between the InGaP layer and the GaAs substrate decreases with increasing Te or Zn impurity concentration. The electrical properties of doped layers were determined by Hall measurements at 300 and 77 K. Room‐temperature carrier concentrations ranging from 2×1017 to 3×1018 cm−3 for n‐type and from 2×1017 to 2×1019 cm−3 for p‐type dopants were obtained reproducibly. The full width at half maximum value of the 300 K photoluminescent spectrum increases with carrier concentration for both Te‐ and Zn‐doped layers. The relative intensity of the 300 K photoluminescent peak increases with electron concentrations up to 3×1018 cm−3 for Te‐doped layers, but it presents a maximum value at 1×1018 cm−3 for Zn‐doped layers. The 14 K photoluminescent spectra show three distinctive peaks and their relative intensities change with hole concentrations. Finally, the rel...

Electrical and optical properties of heavily doped Mg- and Te-GaAs grown by liquid-phase epitaxy

Abstract GaAs epitaxial layers doped with Mg and Te were grown on (100) GaAs substrates by liquid-phase epitaxy with a 6°C supersaturation temperature. Room-temperature carrier concentrations up to 2 × 1019 cm−3 for p-type and 2.6 × 1019 cm−3 for n-type dopants were obtained reproducibly. Carrier mobilities at 77 K in both n- and p-type layers showed a sharp drop at concentrations higher than 2 × 1019 cm−3. The full width at half maximum value and the relative intensity of the photoluminescent spectrum increased and decreased, respectively, with carrier concentrations for both Mg- and Te-doped layers, and showed abrupt slope variations near a carrier concentration of 1 × 1019 cm−3. In Mg-doped GaAs layers, the peak wavelength of photoluminescence spectra increased with hole concentration due to band-gap shrinkage. On the other hand, the photoluminescence peak wavelength decreased with electron concentration due to a Burstein-Moss shift and to band-tailing effects in the Te-doped GaAs layers.

The fabrication of single heterojunction AlGaAs/InGaP electroluminescent diodes

High quality GaAs/AlxGa1−xAs/In0.5Ga0.5P single heterostructure electroluminescent devices have been fabricated by liquid‐phase epitaxy. Three different compositions (x=0.45, 0.58, and 0.85) of AlxGa1−xAs layers were made to compare their properties. Diodes fabricated from these heterostructures have been characterized by electron beam induced current, electroluminescence, quantum efficiency, output power, and current‐voltage measurements. Emission peak wavelengths and full width at half maximum values of the light emitting diodes are, respectively, 652.5, 654.4, and 652.8 nm, and 67, 67, and 75 meV. The peak wavelengths of the light emitting diode shift 6 meV towards the lower‐energy side compared to the photoluminescent peak wavelength of the same electron concentration in the Te‐doped In0.5Ga0.5P layer. For most light emitting diodes, output powers and efficiency are in the range of 50–100 μW and 0.062%–0.1%, respectively.

The doping concentration dependence of the zinc acceptor ionization energy in In0.49Ga0.51P

The doping concentration dependence of the zinc acceptor energy level in In0.49Ga0.51P has been studied and can be expressed as EA=45.75−8.20×10−6u2009P1/3 meV, where P is the zinc acceptor concentration in cm−3. The zinc‐doped In0.49Ga0.51P epitaxial layers were grown on 〈100〉 oriented semi‐insulating GaAs substrates which are in very good crystallinity with a lattice mismatch of only 0.26%.

Highly Strained 1.22-

In this work, the highly strained In0.39Ga0.61As-GaAs lasers grown by metal-organic vapor phase epitaxy were studied. The InGaAs lasers could emit at 1.22 mum under continuous-wave conditions, whereas the threshold current density (Jth) and transparency current density (Jtr) were 140 and 37.2 A/cm2, respectively. To the best of our knowledge, the Jtr was the lowest among the reported InGaAs lasers longer than 1.2 mum. The characteristic temperature (To) was 146.2 K indicating the good temperature stability. These excellent laser characteristics could be attributed to the optimized growth conditions.

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High purity In0.5Ga0.5P epitaxial layers lattice-matched to GaAs substrates were grown by liquid phase epitaxy using a supercooling technique. The lowest carrier concentration of 3×1015 cm-3 has been achieved in the layer grown with a high temperature baked In solution and a supersaturation temperature of 6°C. A deep electron trap located at Ec-0.39 eV was detected by deep level transient spectroscopy, and its concentration is below 22×1014 cm-3.

m InGaAs Lasers Grown by MOVPE

A new version of simple GaAs n+‐n‐δ(p+)‐n‐n+ ultrathin base transistor with U‐groove base contact is demonstrated by molecular beam epitaxy which possesses a circular mesa etched base. The potential barrier height can be directly modulated by the applied base voltage and thus the current can traverse over the barrier by thermionic emission. It is a voltage‐controlled device. Its transconductance increases with increasing collector‐emitter and base‐emitter voltage. The collector current density of the present device is larger than 1.5 kA/cm2 and the transconductance is larger than 200 mS/mm, which are larger than those of the previously reported V‐groove device.