Elsevier

Journal of Crystal Growth

Volume 443, 1 June 2016, Pages 85-89
Journal of Crystal Growth

InAs homoepitaxy and InAs/AlSb/GaSb resonant interband tunneling diodes on InAs substrate

https://doi.org/10.1016/j.jcrysgro.2016.03.021Get rights and content

Highlights

  • Find an optimal condition for growth of homoepitaxial InAs layer by MBE.

  • An InAs/AlSb/GaSb/InAs/AlSb/InAs RITDs RITD has been fabricated.

  • The RITD peak–valley current ratio is 105 at 77 K and 15 at room temperature.

Abstract

In this paper, the optimal conditions for growth of homoepitaxial InAs layer on InAs (001) substrate by molecular beam epitaxy were investigated over wide growth temperatures and As/In flux ratios. The oxide remove process is important and both the As/In flux ratio and growth temperature is in narrow range for InAs homoepitaxy. The high quality homoepitaxy has an RMS surface roughness of 0.26 nm measured by atomic force microscopy. High quality lattice matched InAs/AlSb/GaSb/InAs/AlSb/InAs double barrier resonant interband tunneling diodes was grown on InAs (001) substrate on the optimal condition. It shows high peak–valley current ratios of 105 at 77 K and 15 at room temperature.

Introduction

InAs material has attracted great interests in different device applications due to its advantages of high electron mobility, narrow bandgap and quantum engineering in the 6.1 Å lattice matched system (InAs, GaSb, AlSb, and their alloys). InAs layers with different doping concentration on InAs (001) substrate has been made into devices such as photodetectors [1] and avalanche photodiodes [2]. InAs has also been used in high mobility HEMTs [3]. InAs/AlSb material system has been used to make both type-I resonant tunneling diodes (RTDs) [4] and type-II resonant interband tunneling diodes (RITDs) [5]. They have several advantages over traditional GaAs/AlAs material, such as high-speed [6] and high peak–valley current ratio [7].

Although many reports suggest that high quality InAs can be grown on GaAs substrates, there are few reports about epitaxy InAs on InAs substrates. Homoepitaxy InAs has higher quality and lower defect densities than heteroepitaxy. The first part of this paper is the study of optimum InAs growth conditions by molecular-beam epitaxy (MBE). It shows the relationship between the growth conditions, including the native oxide removal, flux ratio and growth temperature, and the surface roughness of homoepitaxy InAs. The surface roughness was carefully investigated to evaluate material quality by atomic force microscopy (AFM). A further study was carried out on the growth and fabrication of InAs/AlSb/GaSb/InAs/AlSb/InAs double barrier resonant interband tunneling diodes (RITDs) on InAs substrate. The electrical characteristics of RITDs has been investigated.

Section snippets

Experimentation

The growth of all samples was carried out in the Veeco Gen-II MBE system with elemental sources for group III (Ga, Al and In) materials, two crackers to supply As and Sb, and dopant sources (Te, Si and Be). The temperatures of the As cracker and the Sb cracker were both set to 900 °C for As2 and Sb2. In-situ reflection high-energy electron diffraction (RHEED) was used to monitor the surface quality. Beam fluxes were measured by the beam flux monitor. The growth rate of InAs was 0.6 ML/s, which

Homoepitaxy growth of InAs

According to our experiment, the growth rate of 0.6 ML/s for InAs homoepitaxy is high enough to enable the device to be grown in a reasonably short time. We used the oxide desorption temperature (Tod) as the standard temperature, and assumed that the actual Tod of every sample is the same. Then we grew InAs at the temperature which equaled to Tod minus a certain temperature, just like using GaSb surface reconstruction to calibrate GaSb growth temperature.

Firstly we studied the oxide removal

Conclusion

In conclusion, in order to obtain the optimal growth conditions of homoepitaxial InAs layers, the samples were grown at a wide range of substrate temperatures and As/In beam flux ratios. Appropriate deoxidation temperature of InAs substrate is important to get high quality homoepitaxial layer. The results indicated that the InAs layers grown at a temperature of Tod−40 °C with the As/In flux ratio of about 11:1 had the smoothest surface and lowest density defects. The high quality homoepitaxial

Acknowledgments

National Basic Research Program of China (Grant nos. 2014CB643903, 2013CB932904, 2012CB932701 and 2011CB922201), the National Special funds for the Development of Major Research Equipment and Instruments, China (Grant no. 2012YQ140005), the National Natural Science Foundation of China (Grant nos. 61274013, U1037602,61306013, and 61290303), and Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB01010200), China Postdoctoral Science Foundation-funded project (No.

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