Thermal Annealing of Proton‐Bombarded GaAs and  ( Al , Ga ) As

Abstract

A study of the annealing of proton-bombarded, p-type GaAs and (A1,Ga)As revealed different electrical conductivity recoveryeffects, depending on the host crystal and the original dopant species and concentration level. It was found that the dopant dependence of the annealing temperatures was in the order Tz, < TMg < Tae. In fact, whereas a Zn-doped binary system annealed completely at <570~ Ge-doped samples, both binary and ternary, did not recover to better than within a factor of five of their original conductivities, even at temperatures as high as 700~ The Mg-doped ternaries recovered at ~<570~ while equivalently doped binaries acted similarly to the Ge cases in approaching only within a factor of five of their original values at 700~ The ability to place juxtaposed regions of conducting and nonconducting layers in the "bulk" of a multilayered crystal structure was demonstrated. The potential for three-dimensional integration in compound semiconductors, utilizing these effects, is discussed.The bombardment and penetration of a solid by an accelerated charged particle is an old field of study (1, 2) which became important in semiconductor technology with the fabrication of nuclear particle detectors by ion implantation (3). This technique has since become an integral part of silicon-integrated circuit fabrication (4) and is beginning to be used for the construction of compound semiconductor devices and circuits as well (5).The recognition by Foyt et al. (6) that proton bombardment-induced damage in GaAs could be used to produce electrical isolation between adjacent devices, and the subsequent use of this technique by Dyment et al. (7) for the fabrication of stripe geometry double heterostructure lasers that would operate cw at 25~ were two important steps in the development of optoelectronics. This technology depends on the ability to control the generation of regions of high resistivity material by bombardmentinduced carrier removal (8). However, the use of this type of damage has been limited to the preparation of "tubs" (i.e., regions from the near surface to the surface in restricted areas of the slice) of semi-insulating material. This is a direct consequence of the fact that the bombarding ions impinge on the surface from essentially a normal direction, with a patterned attenuator to define which areas of the semiconductor are exposed and which are protected. The result is a pseudo-three-dimensional technology.We present observations that will enable the fabrication of more complex three-dimensional devices based on the interactive effects between the proton bombardment generation of high resistivity in GaAs and (A1, Ga)As, the dopants present in these materials, and a moderately high temperature anneal. We have found that proton-bombarded germanium-doped GaAs and/or (A1, Ga)As can be heated to 600~ and will maintain semi-insulating properties, while an identical treatment of Mg-or Zn-doped material will cause a return to a high conductivity state. In this paper, we shall show our preliminary results and...

Photorefractive quantum wells: transverse Franz–Keldysh geometry

“…Based on relativistic kinematics, approximately 40 atoms are displaced by each proton. 25 However, some of the vacancy-interstice pairs recombine shortly after they are created. The volumedefect densities created by the implant are therefore estimated to be ND 1017 cm- 3 .…”