We present a theoretical analysis and optimisation of the properties and performance of midinfrared semiconductor lasers based on the dilute bismide alloy InxGa1−xAs1−yBiy, grown on conventional (001) InP substrates. The ability to independently vary the epitaxial strain and emission wavelength in this quaternary alloy provides significant scope for band structure engineering. Our calculations demonstrate that structures based on compressively strained InxGa1−xAs1−yBiy quantum wells (QWs) can readily achieve emission wavelengths in the 3 -5 µm range, and that these QWs have large type-I band offsets. As such, these structures have the potential to overcome a number of limitations commonly associated with this application-rich but technologically challenging wavelength range. By considering structures having (i) fixed QW thickness and variable strain, and (ii) fixed strain and variable QW thickness, we quantify key trends in the properties and performance as functions of the alloy composition, structural properties, and emission wavelength, and on this basis identify routes towards the realisation of optimised devices for practical applications. Our analysis suggests that simple laser structures -incorporating InxGa1−xAs1−yBiy QWs and unstrained ternary In0.53Ga0.47As barriers -which are compatible with established epitaxial growth, provide a route to realising InP-based mid-infrared diode lasers.

We optimized an InGaAs/InP Modified Uni-Traveling-Carrier Photodiodes (MUTC-PDs) design with operation frequency above 200 GHz and responsivity greater than 0.14 A/W. Key device design parameters tradeoffs are systematically analyzed in depth.

We present a theoretical analysis of the properties and performance of mid-infrared dilute bismide quantum well (QW) lasers grown on InP substrates. We analyse the band structure of strained InGaBiAs alloys and quantify their potential for the development of mid-infrared semiconductor lasers. In addition to identifying the permissible growth combinations for this class of laser structures, we perform a comprehensive analysis of the performance of a series of ideal laser structures. We investigate the variation of key material and device parameters on the alloy composition, QW thickness and epitaxial strain, and on this basis identify optimised laser structures for emission across the 3-5 µm wavelength range. Our theoretical analysis suggests that InP-based dilute bismide alloys are an extremely promising candidate material system for the development of highly efficient and temperature stable laser diodes operating in the mid-infrared, and also that this class of laser structures is highly compatible with existing InP-based device architectures.

We theoretically analyzed the detailed carrier transport process based on the drift-diffusion model in the InGaAs/InP modified Uni-Traveling-Carrier Photodiode (MUTC-PD) under high optical input power conditions. A high-speed MUTC-PD design was simulated in depth using the commercial simulation software APSYS. The complex interplay between photo-electron and hole transport processes was quantitatively analyzed. The slowdown of hole transit time due to E field reduction in the undoped InGaAs absorber layer dominated the response speed of MUTC-PDs at a high optical power level. The optimized MUTC-PD design has a relatively strong dependence on optical power level. Based on an optimized design, an O–E conversion responsivity around 0.15 A/W and the intrinsic 3 dB bandwidth of 172 GHz were demonstrated when the input optical power density reached 20 mW/μm2. Our simulation analysis results presented here can be utilized for designing broadband MUTC-PDs in future sub-Terahertz free-space data link applications.

A detailed balance model is used with a blackbody radiation function to determine the efficiency of an intermediate band solar cell including carrier losses from the intermediate band. The effect of the energy gap of the host semiconductor is examined as a function of the intermediate band position in the energy gap and the host semiconductor energy gap. Generally the optimum intermediate band level is found to decrease within the energy gap to mitigate the carrier losses and it is found that carrier losses are less detrimental to small energy gap materials. We therefore focus the study on the role of carrier losses in wide bandgap semiconductor intermediate band solar cell systems such as the GaN semiconductor with an Mn impurity band. Experimentally the Mn acceptor level in the GaN energy gap is found to be 1.8 eV above the valence band which is 199 meV off the ideal IB neglecting losses which reduces the efficiency to 21.36%. We demonstrate how carrier losses can be introduced into the system to shift the optimum IB position. Introducing carrier losses of 70% from the intermediate band, shifts the optimum intermediate band position to 1.8 eV above the valence band and increases the efficiency to 23.41%. We compare this to the effect of alloying the GaN and introducing biaxial strain to shift the effective position of the Mn impurity band within the bandgap to increase the efficiency.