Electrical and Optical Characterisation of 100 MeV 197Au Irradiated GaAs

Effect of 100 MeV 197Au implantation, followedby Rapid Thermal Annealing on electrical and opticalcharacteristic is reported. Single crystal n+ GaAssubstrates of orientation have been implanted atroom temperature with 197Au ions to the doses of 1X1012,1X1013, 1X1014 ions/cm2. The as-implanted current-voltage(I-V) characteristic of samples is studied and the opticalinvestigations in IR and mid IR-range have been made.The implanted samples were isochronally annealed byRTA system at different temperatures and the roomtemperature electrical characterization and the opticalinvestigations are reported

Electrical and Optical Characterisation of 100 MeV 197Au Irradiated GaAs.

Effect of 100 MeV 197Au implantation, followed by Rapid Thermal Annealing on electrical and optical characteristic is reported. Single crystal n+ GaAs substrates of orientation have been implanted at room temperature with 197Au ions to the doses of 1X1012, 1X1013, 1X1014 ions/cm2. The as-implanted current-voltage (I-V) characteristic of samples is studied and the optical investigations in IR and mid IR-range have been made. The implanted samples were isochronally annealed by RTA system at different temperatures and the room temperature electrical characterization and the optical investigations are reported

<span style="font-size: 22.5pt;mso-bidi-font-size:15.5pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">Low cost PC-based <i style="mso-bidi-font-style: normal">I<span style="mso-bidi-font-style:italic">-V </span></i>measurement set-up for ion implanted semiconductor devices </span>

64-72<span style="font-size: 15.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">A low cost PC-based system to measure, record and plot current-voltage characteristics of the ion implanted semiconductor samples has been designed and developed. The various modules of the system are programmable voltage source, current to voltage converter and data acquisition system. The programmable voltage source makes use of two 12-bit digital to analog converters, a summing amplifier, a programmable amplifier and a high voltage amplifier stage. This voltage source can be programmed over a voltage span of ± 20 V, in any step voltage desired, up to a minimum step of ± 10 mV. Data acquisition system is developed using a sample and hold circuit, a programmable amplifier and a 12-bit analog- to- digital converter. The gain of programmable amplifier stage can be set through 110 signals from PC. The current can be measured in five different ranges from (0- lμA) to (0-10mA) and the current resolution of the system is ± 0.5 nA. User-friendly software has been developed in Turbo C, in an interactive mode, to store the 1-V data and plot it either simultaneously or later on whenever required. The number of current readings per voltage step can be programmed through the software and their average is recorded. The system shows good accuracy, repeatability, reliability and is relatively inexpensive. The designed and fabricated PC-based I-V set-up has been used to study the I-V characteristics of n+-GaAs substrates implanted with 70 MeV 120Sn ions. Single crystal n+-GaAs substrates of orientation have been implanted at room temperature with 120Sn ions at 70 MeV energy to three different doses of 1×1012, 1<span style="font-size:17.0pt;mso-bidi-font-size:10.0pt;font-family: " times="" new="" roman","serif""="">× 10<span style="font-size:15.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">13 and 1 <span style="font-size:17.0pt;mso-bidi-font-size:10.0pt;font-family: " times="" new="" roman","serif""="">×<span style="font-size:15.0pt;mso-bidi-font-size: 8.0pt;font-family:" times="" new="" roman","serif""="">1014 ions/cm2 <span style="font-size:15.0pt;mso-bidi-font-size:8.0pt;font-family: " times="" new="" roman","serif""="">The implanted samples were isochronally annealed for 10 min in a RTA system at different temperatures in the range 100-300°C. The room temperature I-V curves for the as-implanted sample and samples annealed at different temperatures were recorded and their room temperature resistance values are estimated from them. The I-V behaviour of these samples has been found to be dominated by radiation-induced defect states in the GaAs substrates. </span

Design of microprocessor controlled RTA system for processing of ion implanted semiconductor materials

543-551<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Rapid thermal annealing (RTA) is one of the important techniques used for removal of radiation induced defects in ion implanted semiconductor materials. A complete stand-alone microprocessor controlled RTA system has been designed and fabricated. It uses a 12 kW halogen lamp bank for rapid radiative heating of the sample and provides good temperature ramp-up rate of > 120°C/s up to a temperature of 700°C. A gas line assembly has been provided to carry out the annealing in hydrogen, nitrogen, argon and oxygen gas ambient. The system temperature is programmable in the step of 1°C each up to the maximum attainable temperature of 1080oC. The soak time can be programmed from a minimum of 1 s up to a maximum of 15 min per set temperature. The system has been used for annealing of single crystal GaAs substrates implanted with 70 MeV 56Fe ions with a dose of 1×1014 ions/cm2, in the temperature range 100-600oC. The implanted samples have been investigated by optical transmission measurements over photon energy range 0.1-1.4 eV, after each annealing stage. The mid-gap defect states are annealed out more rapidly than the near-band edge defect states during annealing up to 350°C whereas, the near-band edge defect states are annealed out more rapidly than the mid-gap defect states during annealing between 350-600oC.</span