InGaAsP/InP Light Emitting Transistor (LET) Structures *S
The epitaxial growth of III-V compound semiconductors InGaAs, InAlGaAs, and InGaAsP alloys that match the InP lattice is widely used in the manufacture of electronic and optoelectronic devices, such as heterojunction bipolar transistors (HBTs), light-emitting transistors (LETs), light-emitting diodes (LEDs), laser diodes (LDs), and photodetectors, especially for high-speed electronic and fiber optic communication system applications. PAM-XIAMEN can grow InGaAsP/InP epitaxial wafer for light emitting transistor fabrication. The specific structure is as follows, for reference only:
1. InGaAsP/InP Light Emitting Transistor Structure
1) InGaAsP/InP Epitaxial Wafer for Shallow Ridge LET
| Epi Layer | Thickness | Dopant | Doping Concentration |
| n+ 1.2Q InGaAsP | – | – | – |
| InP | – | – | – |
| p+ 1.2Q InGaAsP base | – | – | – |
| 1.5Q InGaAsP QWs *XX | – | – | – |
| p+ 1.2Q InGaAsP base | – | – | – |
| i 1.2Q InGaAsP collector | – | – | – |
| i InP collector | – | – | – |
| InP buffer | 500nm | – | – |
| InP substrate |
2) InGaAsP/InP Epitaxy for Deep Ridge LET
| Epi Layer | Thickness | Dopant | Doping Concentration |
| n+ 1.2Q InGaAsP | – | – | – |
| InP | – | – | – |
| i 1.2Q InGaAsP | – | – | – |
| 1.5Q InGaAsP QWs *XX | – | – | – |
| i 1.2Q InGaAsP | |||
| p+ 1.2Q InGaAsP Base | – | – | – |
| i 1.2Q InGaAsP collector | – | – | – |
| i InP collector | – | – | – |
| InP buffer | 500nm | – | – |
| InP substrate |
2. About Light Emitting Transistor (LET)
The characteristics of LET require the luminescent semiconductor used to have both high carrier mobility and high fluorescence efficiency. However, the semiconductors currently used for light-emitting transistors mostly come from Field Effect Transistors (FETs) or Organic Light Emitting Diodes (OLEDs). The structure of light-emitting transistors is similar to that of OLEDs, mostly using multi-layer structures such as electron transport layers, hole transport layers, and light-emitting layers. The separation of the charge transport layer and the light-emitting layer reduces the quenching of excitons by charges, which is beneficial for improving light emission device efficiency.
LET produces light faster than LED. Another advantage is that the light intensity can be controlled by adjusting the current. In addition, the third transistor port allows for better control over electrical and optical outputs. The future applications of light emitting transistor include replacing wires in electronic devices with optical fibers to produce higher performance devices.
3. Influence of External Electric Field on Exciton Binding Energy in InGaAsP/InP QWs
The InGaAsP/InP quantum well material has high crystal symmetry and a large saturation electron drift rate. Its electrical properties can be changed by applying an external electric field, which has great advantages in semiconductor optoelectronic devices. Optoelectronics is an important field in the information industry, and exciton emission plays an important role in active light-emitting devices The driving force of device applications has greatly promoted extensive research on excitons. Excitons also have potential applications in solid-state quantum information, and exciton states can serve as effective carriers of quantum information. Preparing various ideal exciton states and coherently controlling them is of great significance for both fundamental and applied research.
Researchers used the variational method under the effective mass approximation to calculate the exciton binding energy in InGaAsP/InP quantum wells as a function of well width and In composition, and also discussed the effect of external electric field on the exciton system binding energy From the calculation results, it can be seen that for InxGa1−xAsyP1−y/InP quantum wells, due to the combined effect of Coulomb interaction and quantum confinement potential, the exciton binding energy increases with the increase of well width when the well width is small. When the well width reaches a certain value, the binding energy reaches a peak and then decreases with the increase of well width The In component has a certain influence on the size of the well width corresponding to the maximum exciton binding energy. As the In component increases, the bandgap of the material decreases, resulting in a corresponding decrease in the well width at the maximum value The influence of electric field on exciton binding energy is not significant within a certain range However, when the electric field is large, electrons and holes are more affected by the electric field, which weakens the exciton effect. These results can provide a theoretical basis for designing InGaAsP/InP quantum well light-emitting devices, like light emitting transistor.
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