Real-time monitoring of low-temperature hydrogen plasma passivation of GaAs

Abstract

By monitoring photoluminescence (PL) in real time and in situ, hydrogen plasma operating conditions have been optimized for surface passivation of native-oxide-contaminated GaAs. PL enhancement is critically dependent on exposure time and pressure because of competition between plasma passivation and damage. Optimal exposure time and pressure are inversely related; thus, previous reports of ineffective passivation at room temperature result from overexposure at low pressure. Plasma treatment is effective in removing As to leave a Ga-rich oxide; removal of excess As increases the photoluminescence yield as the corresponding near-midgap-state density is reduced. Passivation is stable for more than a month. These results demonstrate the power of real time monitoring for optimizing plasma processing of optoelectronic materials.

Ion chemistry in H2-Ar low temperature plasmas

“…In surface engineering H 2 -containing plasmas have a wide range of applications, for example in etching 1 , film deposition 2-7 and surface passivation, hydrogenation and oxide reduction [8][9][10][11] . Furthermore, H 2 -Ar mixtures were successfully applied for hydrogenation of thin film transistors 12 and to control the surface properties of polymers 13 .…”

Quantitative determination of mass-resolved ion densities in H2-Ar inductively coupled radio frequency plasmas

“…H 2 -containing plasmas have a wide range of technical applications in etching 1 , film deposition 2-7 and surface passivation, hydrogenation and oxide reduction [8][9][10][11] . H 2 -Ar mixtures were successfully applied for hydrogenation of thin film transistors 12 and to control the surface properties of polymers 13 .…”

Use of real-time photoluminescence and low-power electron cyclotron resonance hydrogen plasma for passivation of SiN–InP interfaces

“…An initial decrease in the real-time PL signal has also been observed during H plasma treatment of GaAs by Gottscho et al and has been attributed to charging of the sample. 3 The increase in PL, which indicates a reduction in nonradiative centers that ensues, may be attributed to the following processes: ͑i͒ surface cleaning, i.e., removal of native oxides and contaminants; and ͑ii͒ H passivation of the surface defect centers. The decay in the PL signal that follows is due to the deterioration of the surface stoichiometry due to the loss of P from the surface.…”

“…These include dry etching, surface cleaning, and passivation of defects. [1][2][3][4][5] H plasma treatments of InP surfaces have been particularly difficult because of the relative ease with which damage occurs to the surface due to P ablation. Due to excessive H exposure to InP, P is lost as PH 3 , and metallic In droplets are formed on the surface.…”