1.94-μm light-emitting diodes for moisture-content measurements

High-power light-emitting diodes are demonstrated; they are characterized by a quantum efficiency of 5.5%, utilize a symmetric GaAlAsSb/GaInAsSb/GaAlAsSb double heterostructure, have a spontaneous-emission maximum at a wavelength of 1.94 μm, and operate in the temperature range from −80°C to +60°C. A continuous-wave optical power of 3.7 mW and a peak optical power of 90 mW in pulsed operation (τ∼1–5 ms, f=1 kHz) are attained at room temperature. The principal electrical and emission characteristics are given. Pis’ma Zh. Tekh. Fiz. 23, 19–25 (October 26, 1997)     

Scanning electron microscopy of long-wavelength laser structures

New possibilities of scanning electron microscopy, using secondary-and reflected-electron signals, for determining the position of heteroboundaries in long-wavelength laser structures are reported. The formation of the indicated signals in structures of mid-infrared-range lasers of a new type based on type-II GaInAsSb/InGaAsSb heterostructures as well as in the conventional InAsSb/InAsSbP heterostructures is analyzed. The observed characteristic features of the formation of secondary-and reflected-electron signals in these structures as compared with the well-studied AlGaAs/GaAs structures are explained. The results obtained are necessary for accurate determination of an important laser parameter — the position of the p-n junction. It is shown that it is best to use the reflected-electron signal. Fiz. Tekh. Poluprovodn. 32, 1300–1305 (November 1998)     

A low latency asynchronous arbitration circuit

We present an asynchronous circuit for an arbiter cell that can be used to construct cascaded multiway arbitration circuits. The circuit is completely speed-independent. It has a short response delay at the input request-grant handshake link due to both a) the propagation of requests in parallel with starting arbitration and b) the concurrent resetting of request-grant handshakes in different cascades of a request-grant propagation chain