Technology and setup development for thermodiffusion welding of photocathode heteroepitaxial structures (HES) with glass input windows for image intensifier tubes (I~2)

摘要

In GaAs, InGaAs, InGaP - photocathodes for I~2 to bond HES with input glass windows vacuum thermodiffusion welding (TDW) is used. By existing technology of TDW some problems are appeared, that connected with fragility, deformation, thermic matching of materials, also with thermic stresses in welded materials. In this report describe the methods of concrete problem-solving that attend TDW is described. In I~2 production with GaAs-, InGaAs-, InGaP-photocathodes to bond photocathodes HES to input glass windows vacuum thermodiffusion welding in used. To ensure large volume of production a high productivity and reliable setup have been produced and thermodiffusion welding technology has been developed. Vacuum thermodiffusion welding is based on two surface interactions at high-temperature stimulation upon press force. This process can be presented by three stages. At the first stage bonded surfaces are moved near and touched each other as a result from glass detail deformation till physical interaction forces are appeared. Thus physical contact is formed. At the second stage surface activation is occurred, that causes active centres formation and transfer of the atoms from physical adsorption state to chemical adsorbtion state. At this stage the final stage interaction starts that and as a result of it the diffusion process is developed, that gives this processa volume character.