InP/GaInP nanowire tunnel diodes

Abstract

Semiconductor nanowire solar cells with single p-n junction have achieved comparable efficiency to their planar counterparts with substantial reduction of material consumption. Tandem geometry is a path towards even higher efficiency, for which a key step towards realizing such a device is the fabrication of tunnel (Esaki) diodes within nanowires with correct diameter, pitch, and material combination for maximized efficiency. We have fabricated, characterized and compared the electrical characteristics and material properties of InP/GaInP and GaInP/InP nanowire tunnel diodes with band gap combinations corresponding to high efficiency solar energy harvesting. Four different configurations with respect to material composition and doping were investigated. The nanowire arrays were grown with Metal Organic Vapor Phase Epitaxy from Au particles defined by use of nano imprint lithography, metal evaporation and lift-off. Electrical measurements show that the NWs behave as tunnel diodes in both InP (bottom)/GaInP (top) and GaInP (bottom)/InP (top) configurations, exhibiting a maximum peak current density of 25 A/cm 2 , and maximum peak to valley current ratio of 2.5 at room temperature. The realization of NW tunnel diodes in both InP/GaInP and GaInP/InP configurations open up an opportunity for NW tandem solar cells independent of the growth order of the different materials, opening up for flexibility regarding dopant incorporation polarity.

Characterisation of Semiconductor Nanowires by Electron Beam Induced Microscopy and Cathodoluminescence

“…an abrupt heavily doped p ++ /n ++ junction where a tunneling current could flow under voltage 43,44 . Since the depletion region width is a critical parameter for the design of an Esaki diode, EBIC mapping has been used to measure the extension of the space charge region in different wires (Figure 6d) 45 . The quantitative analysis of those maps by tracing the profile along the axis (reported in Figure 6e) allowed to correlate the I(V) characteristic curves of the Esaki diode with the presence of a narrow depletion region in individual nanowires.…”

Electrostatic Control of the Thermoelectric Figure of Merit in Ion‐Gated Nanotransistors

“…[ 5 ] For all these applications semiconducting nanowires have attracted much interest owing to their versatility and unique properties such as their high aspect ratio and ease of realization both for homogeneous nanostructures and heterostructures. These properties have made them promising for thermoelectrics [ 6–9 ] and nano‐electronics, [ 10–13 ] as well as iontronic nanodevices, [ 14–17 ] optoelectronics, [ 18,19 ] sensing [ 20–22 ] and quantum computing. [ 23,24 ]…”

“…[5] For all these applications semiconducting nanowires have attracted much interest owing to their versatility and unique properties such as their high aspect ratio and ease of realization both for homogeneous nanostructures and heterostructures. These properties have made them promising for thermoelectrics [6][7][8][9] and nano-electronics, [10][11][12][13] as well as iontronic nanodevices, [14][15][16][17] optoelectronics, [18,19] sensing [20][21][22] and quantum computing. [23,24] In the quest for high-efficiency thermoelectric materials, a relevant parameter to be taken into account is the figure of merit ZT = σS 2 T/κ, where σ is the electrical conductivity, κ is the thermal conductivity, and S is the material-dependent Seebeck coefficient.…”

Comparison of Triethylgallium and Trimethylgallium Precursors for GaInP Nanowire Growth

“…[ 10 ] For the growth of Ga x In 1– x P NWs, the Ga precursor trimethylgallium (TMGa) is commonly used. [ 11–16 ] However, TMGa has the disadvantage of inefficient pyrolysis at typical NW growth temperatures (400–480 °C), which can complicate growth dynamics. [ 17 ]…”