The physical properties of GaSb are briefly presented and the device implications reviewed. GaSb is a direct gap semiconductor (0.72 eV) capable of being doped either p or n type with good mobilities and it has significant electro-optical potential in the near IR range. As a substrate, or active layer, GaSb can be employed in conjunction with many semiconductors such as (AlGa)Sb or In(AsSb) and has interesting heterojunction potential for detectors and lasers and quantum well structures.

Gallium antimonide device related properties

Anomalous elevations up to 6 μm of the ion‐implanted GaSb surface were observed. This swelling phenomenon is related to the formation of a porous layer and is dependent on the mass, energy, and dose of the implanted ions. A strong amount of oxygen was measured in the porous layers but this oxygen is likely not responsible for the swelling. The behavior of implanted GaSb is very similar to that of InSb previously described.

Anomalous behavior of ion-implanted GaSb

The III‐V compound gallium antimonide (GaSb), which has a relatively narrow band gap, is of increasing importance for the fabrication of optoelectronic devices. However, GaSb was shown to swell during high energy ion implantation. The surface upheaval increased with the dose, energy, and mass of implanted ions, reaching heights of about 1 μm under the most harmful conditions. With the low energies used for secondary ion mass spectrometry (SIMS), i.e., between 1 and 20 keV, a similar behavior was observed under cesium bombardment, with elevations of 100 nm, giving rise to abnormal secondary ion yields and depth profile distortions. Here, the phenomenon has been investigated under cesium and oxygen bombardment, between 1.25 and 14.5 keV, with doses from 1015 cm−2 to above 1017 cm−2. The swelling of the material is confirmed whatever the nature of primary ions. The mechanism is related to the damage caused by the primary ion bombardment rather than to the presence of oxygen. The critical damage threshold of ...

Secondary ion mass spectrometry generates swelling of GaSb: Depth resolution and secondary ion yields

We have measured impact ionization rates in Ga1−xAlxSb at x=0 and 0.08. For these Al contents, the ratio values of the spin‐orbit splitting energy Δ to the energy gap Eg are, respectively, greater and lower than unity. We have determined that the ratio of the ionization coefficients kp/kn is greater than unity for both compositions and that it is much lower (kp/kn≊2) than the value (≳10) determined on our layers for x=0.04. Multiplication noise measurements confirm these results. The comparison to other published data show that the ionization in these antimonide compounds is not yet elucidated.

Impact ionization in Ga1−xAlxSb

Characteristics of ion implantation induced damage in GaSb, and its removal by rapid thermal annealing, are investigated by cross-sectional transmission electron microscopy. Rapid thermal annealing (RTA) has been implemented on implanted GaSb for various temperatures and durations with the semiconductor capped, which avoids Sb out-diffusion and Ga agglomeration during the process. The RTA damage induced in the GaSb wafer was studied by scanning electron microscopy and energy dispersive x-ray spectroscopy. The results of the microscopy study were then used to optimize the RTA recipe and the Si3N4 capping layer thickness to achieve doping activation while minimizing crystalline damage. Results indicate a lattice quality that is close to pristine GaSb for samples annealed at 600 °C for 10 s using 260 nm thick Si3N4 capping layer. Secondary ion mass spectrometry measurement indicates that the implanted Be does not migrate in the GaSb at the used annealing temperature. Finally, electrical characteristics of diodes fabricated from the implanted material are presented that exhibit low series resistance and high shunt resistance suitable for photovoltaic applications.

Characterization of surface defects on Be-implanted GaSb

Be ions are implanted into Te‐doped Ga0.96Al0.04Sb layers grown by liquid‐phase epitaxy. Be distribution is analyzed from secondary‐ion mass spectrometry profiles and is found to be in good agreement with a computed simulation one. Hall‐effect measurements show a complete electrical activity of the Be‐implanted ions. Mesa devices are realized on the Ga0.96Al0.04Sb p+/Ga0.96Al0.04Sb n−/GaSb+ system: Be implantation leads to good quality junctions exhibiting homogeneous multiplication.

Be+ ion implantation in Ga0.96Al0.04Sb epitaxial layers

Implantation of Be+ ions into GaAISb epilayers is used to realize thep + layer of the Ga0.96Al0.04Sb p+/Ga0.96Al0.04Sbn − /GaSbn + (1.55 /Μm) avalanche photodetector whose performances are detailed in Ref. (1). The GaAISb layers are grown using liquid phase epitaxy (LPE); the quality of these as-grown layers is shown through photoluminescence and channeling measurements. The last part of this paper is devoted to the damaging level in the Be+-implanted layers. Some annealing techniques are presented as a mean of restoration of the implanted layers. It is clear from the results that the Be+ ion implantation leads to a low damage level in this III-V compound.

Radiation damage and annealing behaviour in Be + -implanted pure Ga(Al)Sb layers

Be+ implantation into Liquid Phase Epitaxial n Ga 0.96 Al 0.004 Sb has been used in order to study the photodetection characteristics of the resulting p+/n diode, in the multiplication region. The great difference observed between the multiplication in the respective cases of pure electron and hole photoinjections confirms that the room temperature ionization coefficients ratio is very different from unity making this material very promising for an antimonide based Separated Absorption Multiplication Avalanche Photodiode. (SAM APD).

http://ieeexplore.ieee.org/iel5/5436369/5436370/05436584.pdf

Ga 0.96 Al 0.04 Sb Implanted Avalanche Photodiode; Perspective for a 2.55 μm SAM APD Photodetector

Be + ion implantation into Te-doped Ga(Al)Sb ( x Al ≈ 4% ) epilayers was performed to realize the p + layer of a p + /n − GaAlSb/GaSb n + IR avalanche photodetector. A double implantation using 100+50 keV energies and fluences around 10 13 cm −2 is found to be a convenient procedure to produce a junction depth of 0.5 μm. Damage levels created by Be + ions in GaAlSb layers are simulated and investigated through channelling measurements and it is seen that heat treatments (15 min, 450 °C, H 2 ) improve the activation. This paper clearly shows that Be + ion implantation leads to a low damage level in this III–V compound.

A. Pérez

Papers

Be+ ion implantation in Ga0.96Al0.04Sb epitaxial layers

Radiation damage and annealing behaviour in Be + -implanted pure Ga(Al)Sb layers

Ga 0.96 Al 0.04 Sb Implanted Avalanche Photodiode; Perspective for a 2.55 μm SAM APD Photodetector

Be+ ion implantation in Ga(Al)Sb layers: radiation damage