Lateral pnp GaAs bipolar transistor prepared by ion implantation

A lateral pnp bipolar transistor structure has been realised in n-GaAs material using ion implantation. Be ions have been implanted to form the emitter and collector. Proton implantation has been used to reduce the area of the parasitic emitter-substrate diode. First results of a transistor with a current gain of 0.5 are shown.     

Double heterojunction GaAs/GaAlAs I2L inverter

GaAs/GaAlAs double heterojunction I2L inverters with a vertical pnp current source were fabricated by ion implantation and Zn-diffusion into LPE structures. The current gain of the upside-down-operated double heterojunction npn transistor has been improved by a factor of two compared to the gain of the npn transistor of the otherwise similar structure. In addition, the wide-gap junction pnp transistor gives a solution to the critical switch-on problem which can occur when a wide-gap emitter transistor is used for the switching transistor.     

Reduction of dislocations in GaAs and InP epitaxial layers by quasi ternary growth and its effect on device performance

It is shown that strained isoelectronically doped buffer layers grown on GaAs and InP substrates allow one to reduce the dislocation density as well as the deep level concentration. Photoluminescence measurements show an improved near gap luminescence and a reduced deep level emission. This has been also confirmed by DLTS measurements. The higher material quality is also reflected in the device performance. GaAs Schottky diodes (n ˜0.5 · 10¹⁶Cm^-3) exhibit a leakage current of 100 pA up to 50 V reverse bias at room temperature even with large Schottky contact area of 125 μm × 60 μm. This technique allows the quality of electronic and optoelectronic devices to be improved.     

Fabrication and characteristics of ion-implanted GaAs/GaAlAs integrated injection logic inverter

An integrated injection logic inverter has been realised in GaAs/GaAlAs material using ion implantation and Zn diffusion. Si ions have been implanted to merge the current source with the switching transistor, whereas the Be implantation provides the base contact. The shallow p+-emitter of the pnp current source has been fabricated by Zn diffusion. Instead of a lateral pnp transistor, which is typical in I2L technology, a vertical arrangement has been used. This type of transistor shows a better current efficiency and can be fabricated with a better uniformity in terms of base width. First results of an I2L inverter with a vertical pnp transistor are shown.