Ion-beam-induced isolation of GaAs layers by⁴He⁺implantation: effects of hot implants

Abstract

The formation of thermally stable highly resistive regions in n-type GaAs layers during helium ion bombardment at elevated temperatures, where dynamic annealing of radiation-induced defects is substantial, was investigated and presented here. The substrate temperatures were chosen to be room temperature (RT), 100 and 200 • C. Semi-insulating GaAs wafers of (100) orientation were implanted with multi-energy 29 Si atoms to create a flat dopant distribution of about 0.7 µm in thickness. A uniform damage density was formed within the conductive layer by 2 × 10 14 cm −2 helium implantation at 600 keV to isolate the structure. Resistivity and Hall measurements were performed in order to study the evolution of the sheet resistance and Hall mobility as a function of post implant annealing temperature in these resistors implanted at three different temperatures. The samples were annealed in the range 100-800 • C and an optimum isolation of >10 7 ohms/ was achieved for samples implanted at either RT or elevated temperatures after annealing at 400 or 450 • C, respectively. Annealing at higher temperatures returned the resistivity to a value close to that of the starting material and it was found that RT implants recover quicker than elevated temperature implants. The isolated regions exhibited good stability to heat treatment up to 550 or 650 • C for 100 or 200 • C implants, respectively. No such annealing window for the thermal stability of the obtained isolation was found for samples implanted at room temperature. It is believed that isolating defects are more thermally stable in the case of hot implants than those formed by RT implantation.

Implant isolation of Zn-doped GaAs epilayers: Effects of ion species, doping concentration, and implantation temperature

“…[7][8][9][10][11][12][13] Most of those studies have been driven by the need to enhance the current understanding of the physical mechanisms that underlie defect isolation. The results from the comprehensive investigation of de Souza and coworkers [7][8][9][10] suggest that antisite defects created by replacement collisions and/or their defect complexes are responsible for free carrier trapping in GaAs.…”

Probing charge carrier compensation in high energy ion irradiated III–V semiconductor by Raman spectroscopy and Hall measurements

“…Ion irradiation is a well‐established technique for tuning various physical, electrical, optical and mechanical properties of these materials. For example, ion irradiation and subsequent annealing can produce modified layers (both on the surface and deep inside the target) with their electrical conductivity different from that of the surrounding matrix . In case of semiconductors, these energetic irradiated ions produce various types of defects, like vacancies and interstitials, along their path.…”

Planar InAs photodiodes fabricated using He ion implantation

“…He, O or B) to create highly resistive regions [14]. A number of studies have been performed on the use of He implantation in GaAs to create highly resistive regions [15,16]. In these studies it was shown that high resistive regions are formed through the creation of deep 'mid-band' traps which restrict the flow of charge.…”

“…For example Oxygen implantation into InGaAs results in resistances in the range 10 4 -10 5 /Square [16], while Iron and Krypton implantation have both been used to increase the sheet resistance a further order of magnitude to 10 6 /Square [19]. Additionally investigation of proton implantation in InSb has been shown to result in n-type material becoming p-type, due to traps not being created in the middle of the bandgap [17].…”