摘要:

In the paper we consider how the Rutherford scattering of high-energy (MeV) light ions can be used as a nondestructive technique for studying thin films on semiconductor surfaces. A number of examples are discussed which illustrate the potential and limitations of the technique for studying semiconductordevice structures.

DOI:10.1049/ij-ssed.1977.0001

出版商:IEE    

年代:1977

数据来源: IET

摘要:

For bulk c.c.d.s, the depth of the potential well is obtained by measuring the differential conductance perpendicular to the c.c.d. transfer direction. A test field-effect device, the measuring method and the circuitry are presented. An example shows the ability of the method to detect parasitic potential wells in the transfer direction.

DOI:10.1049/ij-ssed.1977.0002

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The delay-, rise-and decay-times of several types of single-heterostructure l.e.d.s differing in junction area, active-layer doping and width have been measured. A theory is presented which considers the influence of these parameters on the l.e.d. time response. A comparison of the measured and calculated pulse behaviour is given. With a proton-bombarded small area l.e.d. a transmission rate of 300 Mbit/s has been achieved.Die Verzögerungs-, Anstiegs- und Abfallzeit von verschiedenen Typen von Single-Heterostruktur LED's wurde gemessen. Die Dioden unterschieden sich in der Fläche despn-Übergangs, der Dotierung und der Weite der aktiven Zone. Eine Theorie wird dargestellt, die den Einflufβ dieser Parameter auf das Zeitverhalten beschreibt. Das berechnete und gemessene Impulsverhalten wird verglichen. Mit einer protonenimplantierten LED wurde eine Übertragungsrate von 300 Mbit/s erzielt.

DOI:10.1049/ij-ssed.1977.0003

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A GaAlAs/GaAs heterojunction transistor has been made using liquid-phase epitaxy. The emitter stripe was 10µm wide by 100µm long. The base and emitter had equal impurity content around 5 × 1023/m3but, with the wide band gap GaALAs emitter, low-frequency current gains approaching 2000 were found. This is amongst the highest so far recorded for this type of transistor. The alpha-cutoff frequency was estimated to be around 1 GHz, but the unity gain frequency was experimentally as low as 100 MHz. This was attributed to high r.f. resistance, possibly caused by the Schottky barrier contact to the base region. When the basecollector region was driven close to primary breakdown, current densities in excess of 3 × 107A/m2could be obtained without secondary breakdown occurring, at least for the duration of the bias pulse. This appeared to be about an order of magnitude better than for a comparable Si transistor. Avalanche multiplication could then increase the unity gain frequency to 400 MHz.

DOI:10.1049/ij-ssed.1977.0004

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A model for the drift region of high-efficiency IMPATT diodes is described. Results obtained using the model are presented and demonstrate the existence of important drift-region tuning effects.

DOI:10.1049/ij-ssed.1977.0005

出版商:IEE    

年代:1977

数据来源: IET

摘要:

New techniques for computing the large-signal behaviour of multicavity klystron amplifiers have shown how significant increases in their efficiency can be realised in practice. The computing methods have further benefits of increased speed and accuracy in comparison with previous techniques. A new compressible-cylinder model of the electron beam has been developed, together with a technique for the direct summation of the power transferred to the output cavity. With the new model, space-charge force is evaluated quickly enough for both final gap voltage and final drift length to be set for maximum efficiency independently, and, typically, within half a minute on a fast computer. The rapid determination of best efficiency then permits repeated runs to find the influence of other design parameters, within reasonable totals of computer time. Optimisation of efficiency by computer-controlled variation of design parameters has also been investigated, but its inherent limitations make it unlikely to yield optimum sets of parameters inexpensively. An experimental 4-cavity klystron for u.h.f. t.v. transmission has shown saturated efficiency of 51%, compared with typical values for existing tubes of 35–40%; the tube outline and external circuitry were unchanged, while the t.v. performance was demonstrated to be similar to that of the standard tubes.

DOI:10.1049/ij-ssed.1977.0006

出版商:IEE    

年代:1977

数据来源: IET