Selective Area Heteroepitaxy of p-i-n Junction GaP Nanopillar Arrays on Si (111) by MOCVD

Wonsik Choi,Shizhao Fan,Minjoo Larry Lee,Hsien-Chih Huang,Parsian K Mohseni,Xiuling Li

doi:10.1109/jqe.2022.3151971

Wonsik Choi, Shizhao Fan + Show 4 more

Open Access

https://doi.org/10.1109/jqe.2022.3151971

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Abstract

Gallium phosphide (GaP) is an important optical material due to its visible wavelength band gap and high refractive index. However, the bandgap of the thermodynamically stable zinc blende GaP is indirect, but wurtzite (WZ) structure GaP is direct bandgap. In this work, we demonstrate high-quality and dense GaP vertical nanopillar (NP) array directly on Si (111) substrates through selective area epitaxy (SAE) by MOCVD for the first time, through systemic studies of the effect of TMGa flow rate, growth temperature, and V/III ratio. Uniform GaP NPs are grown over a patterned <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$400\,\,\mu \text{m}\,\,\times 400\,\,\mu \text{m}$ </tex-math></inline-formula> area with 97.5% yield. Arrays of GaP vertical p-i-n NP diodes are demonstrated with a ideality factor and rectification ratio of 3.7 and 103, respectively. With the high yield of hexagonal structure and electrically proven device quality of GaP NPs through this growth method, this work represents a significant step in achieving GaP NP based optoelectronic devices, such as micro-LEDs emitting in the green wavelength range.

Highlights

The vapor-liquid-solid (VLS) mechanism has been used to grow nanowires (NWs) for decades due to its precise control of high crystal quality growth for many III-V semiconductor NWs.[1], [2] it is not always desirable for VLS grown NWs to be monolithically integrated in conventional silicon (Si) based technology, because the metal particle used for VLS growth could be incorporated as an unintentional impurity dopant in Si and induce deep levels that degrade device properties by trapping electrons and holes.[3]
We demonstrate dense, ordered, and uniform Gallium phosphide (GaP) NW array grown on Si (111) substrates by MOCVD via the selective area epitaxy (SAE) mechanism for the first time
Since GaP NPs are preferentially grown along the B direction,[16] the substrates of NPs require the selection of the (111)B-oriented surface to achieve vertically aligned NPs; while on the (111)A-oriented surface, III-V NPs grow along three tilted direction (19.5° from the surface).[1], [8], [10] unlike III-V materials, Si does not have surface polarity; the surface of Si has to be modulated as (111)B-oriented in order to control the direction of NPs.[8], [10] To achieve group-V terminated surface on the Si(111) substrate, 50 sccm (2.2 × 103 mol/min) of PH3 was introduced during the ramping up/native oxide desorption step (750 °C for 10 min)

Summary

Introduction

The vapor-liquid-solid (VLS) mechanism has been used to grow nanowires (NWs) for decades due to its precise control of high crystal quality growth for many III-V semiconductor NWs.[1], [2] it is not always desirable for VLS grown NWs to be monolithically integrated in conventional silicon (Si) based technology, because the metal particle used for VLS growth could be incorporated as an unintentional impurity dopant in Si and induce deep levels that degrade device properties by trapping electrons and holes.[3].

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