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Ohmic contacts of Au and Ag based Zn containing alloys on p -type Ga 0.47 In 0.53 As have been studied using intermediate layers of Ti and Ni, respectively. Low specific contact resistance in the order of 10 −5 Ωcm 2 are achieved. In case of AuZn alloy, the Ti intermediate metal layer causes higher contact resistances together with a worse contact morphology in contrast to Ni intermediate layers. However for AgZn contacts Ti adherent layers improve the contact resistances, especially for lower alloying temperatures. Moreover these contacts exhibit significant smoother interfaces as revealed by TEM micrographs. Thus AgZn contacts apply best to low resistive contacting of very thin p -layers forming e.g. the base of a ballistic device.

Highly doped GaAs substrate material (doping level ⩾ 10 18 cm −3 ) has been implanted with 350 keV O + ions with doses of 10 14 – 10 16 cm −2 to produce high resistivity layers which are stable at high temperatures. LPE growth of flat GaAs epilayers onto the implanted wafers was achieved up to doses of about 1 × 10 15 O + /cm 2 and 5 × 10 15 O + /cm 2 for RT and 200°C implants, respectively. N-o-n and p-o-n structures (o: oxygen implanted) were fabricated in which breakdown voltages of up to 15 V were obtained. Examples for application of this isolation technique are shown.

Ga 0.47 In 0.53 As epitaxial layers on InP substrate have been subjected to proton bombardment. The resistivity increases up to 10 4 Ω cm for 10 14 H + /cm 2 in p -type and 3 · 10 16 H + /cm 2 in n -type a 0.47 In 0.53 As implanted at 77 K. Proton bombardment at 300 K showed this increase in resistivity only for p -type material. Channeling experiments indicated that the damage of the lattice which seems to be responsible for the resistivity increase of n -material can be produced only at low temperature with doses of the order of 10 16 H + /cm 2 . Crystalline layers implanted with high dose showed blistering effects after heat treatments.

Zusammenfassung Bei der Silizium-Planar-Technologie ist es wunschenswert, die spezifischen Flachenwiderstande der Basiszone neben und unterhalb des Emitters, sowie der Emitterzone und die Kontaktwiderstande zu kennen. Eine geeignete Methode wird beschrieben. Sie benutzt neben anderen Strukturen einen Transistor mit Tetrodenstruktur. Die Dimensionen der notwendigen Photomaske werden angegeben.