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The lattice constants and long wavelength cutoffs of these alloys are depicted as red lines in Figure 1. The InAs/GaAs alloy is referred to as In xGa 1-xAs, where x is the proportion of InAs and 1-x is the proportion of GaAs. The relationship between the lattice constant and the long wavelength cutoff of the four ternary alloys in the InGaAsP family are shown in Figure 1. The lattice constants range from 5.4505 Å (GaP) to 6.0585 Å (InAs), with GaAs at 5.6534 Å and InP at 5.8688 Å. The challenge is that not only does the energy bandgap depend on the alloy composition, so also does the resulting lattice constant. Quantum Efficiency of standard InGaAs is shown in blue quantum efficiencies of two extended wavelength alloys X=0.74 (green) and X=0.82 (red) are also shown, as well as the spectral response of silicon.īy mixing two or more of the binary compounds, the properties of the resulting ternary and quaternary semi-conductors can be tuned to intermediate values. This “long wavelength cutoff” works out to 3.75 μm for InAs and 0.55 μm for GaP, with InP at 0.96 μm and GaAs at 0.87 μm. A semiconductor will only detect light with photon energy larger than the bandgap, or, to put it another way, with a wavelength shorter than the cutoff wavelength associated with the bandgap. Largely, the electrical and optical properties of a semiconductor depend on its energy bandgap and whether the bandgap is “direct” or “indirect.” The energy bandgaps of the 4 binary members of the InGaAsP quaternary system range from 0.33 eV (InAs) to 2.25 eV (GaP), with InP (1.29 eV) and GaAs (1.43 eV) falling in between. The relationship between the Lattice Constant and the long wavelength cutoff of the 4 ternary alloys in the InGaAsP family. As gallium and indium belong to Group III of the Periodic Table, and arsenic and phosphorus belong to Group V, these binary materials and their alloys are all III-V compound semiconductors. In a more general sense, it belongs to the InGaAsP quaternary system that consists of alloys of indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), and gallium phosphide (GaP). Indium gallium arsenide, or InGaAs, is an alloy of gallium arsenide and indium arsenide.