Comparison of Diffused and Implanted InSb pn-photodiodes Performance
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
In this project, two different methods for fabrication of InSb p-n photodiodes were compared. Ion implantation with Mg as a standard way to fabricate InSb p-n diodes was compared to in-diffusion of zinc atoms from the gas phase using a metal organic vapor phase epitaxy (MOVPE) system. The application of this method to the InSb system has not been previously reported. A Monte-Carlo-based simulation program (SRIM: Stopping and Range of Ions in Matter) was utilized to simulate and extract doses and energies of Mg ions to have different depths for p-doped regions with 1E19 cm
-3concentration. Diffusion runs were performed at three different temperatures of 400, 440 and 475 °C for 15 minutes. Dark current and photoresponse measurements were performed on different doped areas as a function of temperature and detector bias for all samples.
Samples diffused at high temperatures (440 and475°C) showed a high leakage current and were highly conductive. Measurements on devices with different areas revealed that surface leakage constitutes the main part of the dark current. The estimated quantum efficiency of the implanted and diffused samples is roughly 30 percent. Secondary ion mass spectrometry (SIMS) measurements were performed on diffused samples and a high concentration of dopants at the surface with a narrow profile was observed. However, the samples annealed at the higher temperatures of 440 and 475°C didn't show any significant change in the diffusion profile as compared to the sample annealed at 400°C. This is suggested to be due the zinc desorption from the surface.
For optimized annealing time, flow rates and gas partial pressures for the diffusion technique combined with some measures for inhibiting the surface leakage (e.g., surface passivation) this can be a viable alternative to the ion implantation technique for making InSb photodiodes.
Place, publisher, year, edition, pages
2011. , 63 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-102831OAI: oai:DiVA.org:kth-102831DiVA: diva2:556848
Master of Science - Nanotechnology
Hammar, Mattias, Professor