Junction Elements Research Articles

ゲルマニウム-インジウム合金形P-N接合素子のアルカリ性電解および酸性化学エッチング

After-etching of semi-conductor P-N junction element is a very important process for carrying out proper action of transistor or diode upon the device, in which indium pellet is alloyed with single crystal germanium pellet.In the alloying process, there were produced thermal stress, crystal imperfections, irregularity, and some contaminations on the boundary and around the periphery of P-N junction at the alloying temperature. These imperfections produced low inversed voltages, VCBO and VEBO; made increase or drift of saturation currents, ICBO and IEBO; made larger noise figure with low gain; made smaller amplication factor; and made the life shorter for instability in electric action.The techniques for removing these imperfections prevailed hitherto are as follows.(1) Electrochemical etching(2) Chemical etching(3) Supersonic etching(4) Electron beam or ion spatteringThe above techniques (3) and (4) were suitable for the mass production of germanium type transistor (1-10MHz class) and the studies of these techniques have been pursued as follows.(A) Alkaline electrolytic etching(B) Alkaline electrolytic etching combined with acid chemical etching(C) Acid chemical etchingThe above item (C) showed the best result in electric characteristics and stabilization for accelerated life test.This paper reports the results of experiments on alkaline electrolytic etching for 10MHz class transistor and its after-treatment.The optimum condition for the element was as follows.Electrolyte……KOH 30%aq. solutionCurrent density……DC 60mA. per one elementEtching time……3s. x 4 pulsesThe author got high value of VCBO at low value of rbb' but the average value of VEBO was much lower than VCBO. In the testing of ICBO and IEBO by diode curve tracer, leakage currellt of several μA was often found out in some specimens before the avalanche break down.The latter half of this paper describes the acid chemical etching performed after the electrolytic etching. K+ ion adsorbed around the periphery of P-N junction was removed and the junction element, slightly etched by acid Chemical etching, was researched by the behavior of VEBO. The Composition of the after-acid etching. solution and the specification for the etching were as follows.Pure water……6vol.H2O2……2vol. (30% reagent)HF……1vol. (49% reagent)Etching temperature……room temperatureEtching time……5-20s.As the results of experiments, the increase of VEBO and the decrease of surface leakage current were confirmed.

ゲルマニウム-インジウム合金形P-N接合素子の酸性化学エッチング

The previous report, Part 1, described the merits of alkaline electrolytic etching combined with acid chemical etching for Ge-In alloyed junction element. However, this technique needed a lot of processes in after-etching. On the other hand, acid chemical etching deteriorated the mechanical structure of P-N-P alloyed junction element for high frequency use. But, the above demerits could be eliminated by mixing of water, hydrogen peroxide, and hydrofluoric acid in proper ratios. The technique of acid chemical etching is used for the production of high frequency transistor. The results of experiments showed high inversed voltages, VCBO and VEBO, and stability of other electric characteristics.The specifications of the etchants for experiments were as follows.Etchant group Composition (in vol. ratio)154 etchant H2O:H2O2:HF 1:5:4253 etchant H2O:H2O2:HF 2:5:4433 etchant H2O:H2O2:HF 4:3:3By the improved acid etching with 154 etchant (in etching for 40s), the best results were obtained in electric characteristics and mass production.

The fine structure of the maxillary gland of the brine shrimp, Artemia salina: The efferent duct

The gross morphology of the maxillary gland of the adult brine shrimp, Artemia salina, was studied by light microscopy, and some features of Warren's (1938) original description of the gland were confirmed. Each gland consists of two parts: an end-sac and an efferent excretory duct. The end-sac is centrally located, and around it the efferent duct coils, making three loops before continuing as a slender terminal duct which opens to the outside via an aperture on the second maxilla. The fine structure of the end-sac epithelium is remarkably similar to that of the visceral layer of Bowman's capsule of a vertebrate nephron. The cells of the end-sac are highly branched and possess regularly arranged foot processes and junctional elements similar to “filtration slit membranes”. The cytoplasm of these cells contains numerous, membrane-bounded inclusions of unknown origin and function. On the basis of ultrastructural findings, it is postulated that formation of primary urine involves ultrafiltration.

Melanocytic Tumors of Domestic Animals

A tentative classification of melanocytic tumors of dogs is proposed. A canine melanocytic nevus with microscopic features similar to an active human junction nevus undergoing malignant transformation is described. Canine compound nevi appear to originate from melanocytes that have dropped off the epidermis or hair follicles; malignant transformation may occur. The life cycle of melanocytic nevi of dogs is unknown. Fibrous dermal melanocytoma of the dog appears to be equivalent to the common blue nevus of man. In dogs, nearly all oral melanocytic tumors are malignant, while most cutaneous lesions are benign. The ammoniacal silver nitrate technique is useful in demonstrating premelanin in many amelanotic melanomas of dogs. Canine malignant melanoma may originate de novo from melanocytes in epidermis and oral epithelium, and from junctional or dermal elements of canine melanocytic nevi. Differences and similarities between canine and human malignant melanomas are cited.

Melanocytic tumors of domestic animals with special reference to dogs

A tentative classification of melanocytic tumors of dogs is proposed. A canine melanocytic nevus with microscopic features similar to an active human junction nevus undergoing malignant transformation is described. Canine compound nevi appear to originate from melanocytes that have dropped off the epidermis or hair follicles; malignant transformation may occur. The life cycle of melanocytic nevi of dogs is unknown. Fibrous dermal melanocytoma of the dog appears to be equivalent to the "common" blue nevus of man. In dogs, nearly all oral melanocytic tumors are malignant, while most cutaneous lesions are benign. The ammoniacal silver nitrate technique is useful in demonstrating premelanin in many amelanotic melanomas of dogs. Canine malignant melanoma may originate de novo from melanocytes in epidermis and oral epithelium, and from junctional or dermal elements of canine melanocytic nevi. Differences and similarities between canine and human malignant melanomas are cited.