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carried out. LPE growth at T » 530°C enabled obtaining lattice matched heterostructures with 19% indium in the active layer In₀.₁₉Ga₀.₈₁As₀.₁₆Sb₀.₈₄/Al₀.₂₄Ga₀.₇₆As₀.₀₄Sb₀.₉₆ and photodetectors with lc = 2.25 um. By increasing the temperature of epitaxial growth to 590°C In₀.₂₃Ga₀.₇₇As₀.₁₈Sb₀.₈₂/Al₀.₃₀Ga₀.₇₀As₀.₀₃Sb₀.₉₇ heterostructures (with 23% indium content) suitable for photodetectors with lc = 2.35 um have been obtained. Mesa-type photodiodes were fabricated by RIE in CCl₄/H₂ plasma and passivated electrochemically in (NH₄)₂S. These devices are characterised by differential resistance area product up to 400 Wcm² and the detectivity in the range the range 3´1010-2´1011 cmHz¹/²/W, in dependence on the photodiode active area and cut-off wavelength.
DH lasers and for wide gap window layer in photodetectors operating at wavelengths up to 2,4 um. Among various techniques of growing epitaxial layers of III—V semiconductors, liquid phase epitaxy (LPE) still remains interesting method due to its simplicity and satisfactory results.
photoelectron spectroscopy (XPS), atomic force microscopy (AFM) were used to characterize of the superficial sulfide layers. Our results show that sulfide pretreatment in 1M Na2S in isopropanol and annealing under flowing H2 (T= 640°C, t = 1 h) is the best technique of surface preparation of GaSb substrate prior to epitaxy (the thickness of superficial oxide layer is about d = 0,8 nm with minimal surface roughness d= 0,23 nm.
increased up to 2 times by an additional Microwave Downstream (MVDS). Smooth etched surface morphologies were obtained at low and medium RF power densities. Anisotropy of etching was evaluated by measurements of sidewall profiles. Highly anisotropic etching and smooth etched surfaces were observed at optimum conditions (RIE 25 W, BCl3 6 Pa). Operating under these conditions the mesa structures of the detectors and of the double ridge waveguide lasers are fabricated by photolithography. An circular grating for high-efficiency Surface Emitting Lasers is presented to.
etched surfaces was examined using both optical Nomarski and scanning electron microscopy; the etch depth was measured on patterned substrates by means of a Tencor Alpha-step profilometer. By adjusting RIE parameters: P = 30 W, CCl₂ F₂/H₂ = 1.12, p= 185 µbar, submicron size features with vertical side walls have been obtained in niobium films.
order to exploit this potential considerable advances in processing technology, including controlled mesa etching and photodiode surface passivation techniques are required. This paper deals the processes of wet and dry etching of GaSb-based compounds in order to form and passivate GaSb/Ga₀.₇₈In₀.₂₂As₀.₁₈Sb₀.₈/Ga₀.₆₆Al₀.₃₄As0.₂₅Sb₀.₉₇₅ PD mesa sructures. HCL + H₂O₂ + H₂O solutions and CCL₄/H₂ plasmas have been used for masa etching and thier results on mesa profile and etch depth control have been compared. For mesa passivation a surface treatment in (NH₄)₂S water solution was carried out. Examination of PD performance through the measurments of current-voltage and spectral responsivity characteristic have shown that unpassivated photodode structures are characterized by darc current Id=5 ÷ 10 µA at reverse bias UR = -1 V, and quantum efficiency ƞ = 0.5 ÷ 0.7 at ʎ = 2.3 µm and T = 300 K. reduction of dark curent to Id ≤ 3 µA has been obtained for GaSb/GaAlAsSb mesa structures processed in (NH₄)₂S.
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