GaP is one of the compound semiconductor materials which has a large market share and whose developement began a long time ago and has been extensively studied. The reason why GaP was first developed was because it had a possibility for light emitting diodes (LEDs). Since GaP has a comparatively large bandgap (2.26 eV), it is possible to make LEDs of various colors such as red, yellow and green by controlling the dopants.1
The physical properties of GaP2 are summarized in Table 7.1. The melting point of GaP is rather high at 1467 C and the dissociation pressure of P at the melting point is as high as 39 7 atm. GaP has a wide bandgap as wide as 2.26 eV so that it is used as LED material for various colors. Even though GaP is an indirect transition material, LEDs have been realized by appropriate doping.
| Crystal Structure | zincblende |
| Lattice Constant | 5.4495 |
| Density | 4.1297 g/cm 3 |
| Melting Point | 1467 C |
| Linear Expansion Coefficient | 5.3 5.81 10 -6/deg |
| Thermal Conductivity | 1.1 W/cm K |
| Dielectric Constant | 11.1 |
| Refractive index | 2.529 |
| Bandgap at Room Temperature | 2.261 eV |
| Intrinsic Carrier Concentration | 5 10 15 cm -3 |
| Electron Mobility | 200 cm 2/V sec |
| Hole Mobility | 120 cm 2/V sec |
| Intrinsic Resistivity | 2 l0 16 ? cm |
Fig. 7.1 shows the phase diagram of GaP.3 Jordan et al.4 have calculated thermodynamically the densities of Ga vacancies and P vacancies...
TABLE OF CONTENTS 
