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Investigates the infrared reflection of gallium nitride (GaN) and aluminum gallium arsenide (AlGaAs) thin film heterostructures. Identification of the individual layers of GaN and AlGaAs; Observation of the A[sub 1](LO) phonon modes; Presence of thin aluminum nitride buffer layer.

A large increase in the electrical activation of sulfur coimplanted with nitrogen in GaAs is observed within a thin (<500 Å) near-surface region. A free electron concentration as high as 1.5x10[sup 19] cm-3 is observed in this layer, which is a factor of 5 higher than in a GaAs sample implanted with S only. The high free electron concentration in this thin layer is the result of the incorporation of N on the As site which forms a thin dilute GaN[sub x]As[sub 1-x] alloy layer. The increased electrical activity of S in this layer is explained by the N-induced modifications of the conduction band as predicted by the band anticrossing model. The measured free electron concentration is consistent with a GaN[sub x]As[sub 1-x] alloy layer with x∼0.3%. The results have important practical implications on the fabrication of low-resistance, nonalloyed ohmic contacts to n-type GaAs. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have achieved a large increase of the activation efficiency of sulfur atoms implanted into GaN[sub x]As[sub 1-x] thin films. For thin films with only 0.8% N content, we find a maximum free electron concentration of >6x10[sup 18] cm[sup -3] for implanted S concentration higher than 10[sup 19] cm[sup -3], about 20 times larger than that in semi-insulating GaAs implanted and annealed under the same conditions. This large increase of the free electron concentration can be quantitatively explained with the recently developed band anticrossing model. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: GaAs blocked-impurity-band (BIB) photoconductor detectors have the potential to become the most sensitive, low noise detectors in the far-infrared below 45.5cm−1 (⩾220μm). We have studied the characteristics of liquid phase epitaxial GaAs films relevant to BIB detector production, including impurity band formation and the infrared absorption of the active section of the device. Knowledge of the far-infrared absorption spectrum as a function of donor concentration combined with variable temperature Hall effect and resistivity studies leads us to conclude that the optimal concentration for the absorbing layer of a GaAs BIB detector lies between 1×1015 and 6.7×1015 cm−3. At these concentrations there is significant wave function overlap which in turn leads to absorption beyond the 1s ground to 2p bound excited state transition of 35.5cm−1 (282μm). There still remains a gap between the upper edge of the donor band and the bottom of the conduction band, a necessity for proper BIB detector operation. [Copyright &y& Elsevier]